Led by President Carter and Vice Premier Teng Hsiao-ping, the United States and China celebrated a day of reconciliation in Washington yesterday.

With hopeful words and restrained allusions to the bloodshed and enmity of decades past, the two leaders sought in private talks and public ceremony to establish the basis for a new relationship between their nations.

The day and their efforts were marred, however, by the bitter chants of protesters parading in the cause of Taiwan, the jilted party in this new diplomatic match, and by the startling shouts of two Maoist demonstrators who infiltrated the White House welcoming ceremony with press credentials and cried out "murderer" and "traitor" at Teng from less than 35 feet away.

The two protesters were silenced and hustled away by police, but last night about 400 of their Maoist colleagues of a radical communist group clashed violently with police in Lafayette Park across from the White House. The Maoists hurled bottles, metal weights and other projectiles, and police counterattacked on horseback and on foot. There were 69 arrests and about 50 injuries.

Inside the executive mansion, meetings that consumed 3 hours and 45 minutes in two sittings took place in the quiet of the Cabinet Room, with little or no notice of the turbulent emotions outside. The White House said Carter and Teng covered global questions in the morning session and regional affairs of Asia and other areas in the afternoon. A final Carter-Teng business meeting today is expected to concentrate on trade, communications and other bilateral matters.

In the first of the Cabinet Room sessions, Carter said it was "an historic occasion -- the first time in 200 years that the United States and China have normal relations based on equality." For his part, Teng called the festivities "a warm and grand welcome" and predicted that "this visit will be successful."

One subject believed to have been discussed on a top-priority basis is the puzzling and ominous buildup of 10 to 12 Chinese divisions, close to 100,000 men, within striking distance of the Sino- Vietnamese border. Informed U.S. sources said the buildup, which has taken place during the three weeks since the fall of most of Cambodia to Vietnamese-backed insurgents, includes the transfer of more than 150 Chinese warplanes to the Vietnamese border area.

China is also reported to be evacuating large numbers of civilians as well as troops from the area close to its Soviet border, suggesting preparations to blunt a Soviet counterstrike against possible Chinese action in the south. In recent days, the United States has repeatedly warned China, the Soviet Union and Vietnam against military action against one another.

Whatever the level of openness and intensity of discussions inside the White House, only the sketchiest description of them was made public. The Chinese leader, believed by U.S. officials to be unsurpassed in his political power at home, said "there were no boundaries to the number of questions we discussed, from the earth to the heavens."

The White House said Carter accepted in principle a formal invitation to visit China, and Teng accepted in principle an invitation for his nominal superior, Communist Party Chairman and Premier Hua Kuo-feng, to visit Washington. No date was set for either trip.

The public words exchanged at the welcoming ceremony on the White House South Lawn and at a state dinner last night were so guarded as to be almost bland. Teng did not repeat his usual harsh attacks against the Soviet "polar bear," most recently stated in an interview with Time magazine published yesterday.

He said in the welcoming ceremony that "the world today is far from tranquil... The factors making for war are visibly growing," without naming the source of the dangers he sees. In his dinner toast, Teng repeated the substance of the prior official statements by the two nations, in the Shanghai Communique of 1972 and the Normalization Communique of last December, opposing "hegemony," which is the Chinese codeword for Soviet expansionism. He did not mention the Soviet Union by name.

The State Department announced that no formal communique will be issued at the end of the current talks, an arrangement evidently agreed on over dinner Sunday at the home of national security affairs adviser Zbigniew Brzezinski.

Secretary of State Cyrus R. Vance said the usual Chinese practice is to issue communiques only on special occasions, and he laughed when incredulous reporters retorted that this extraordinary first visit by a ranking Chinese communist leader certainly seemed to be a special event.

The omission of a final communique will make time-consuming diplomatic haggling over its wording unnecessary. Moreover, it will avoid the exposure of differences in viewpoint over the Taiwan question, Korea, the strategic arms limitation treaty (SALT) and detente with the Russians, all matters on which the leaderships of the two countries disagree.

There was no mention of the Taiwan issue in the public speeches by either Carter or Teng, and White House press secretary Jody Powell refused to say whether the matter had been discussed during the Cabinet Room meetings. The island bastion, which is considered a Chinese province by the Peking regime but had been a full-fledged U.S. ally for most of the past 30 years, is a very delicate political question on both sides and was the main stumbling block to earlier normalization of diplomatic relations.

Carter spoke of the occasion as "a time of reunion and new beginnings ... a day of reconciliation when windows too long closed have been reopened." He stressed the benefits of bilateral cooperation between the most powerful nation of the capitalist West and the communist giant of Asia, whose teeming millions comprise about one-fourth of all mankind, and said nothing that would suggest the kind of global anti-Soviet alliance that has caused apprehension bordering on alarm in Moscow.

Carter noted in his welcoming speech that past relations with China had been marred by "misunderstanding, false hopes and even war." A few minutes later, posing for pictures with Teng in the Oval Office, Carter recalled that as a young U.S. Navy submarine officer in 1949 he was in the Chinese port of Tsingtao as communist armies surrounded the city and the Nationalist regime collapsed. Teng, by coincidence, was a political commissar of the forces closing in on the city.

"The vice premier is your guest now," said Brzezinski to Carter, within earshot of reporters and photographers. "If things worked out differently, you would have been his guest -- in a very special way."

Teng, in his welcoming speech, noted that the United States and China "fought shoulder-to-shoulder in World War II against fascism," referring to the days when Chinese nationalists and Chinese communists formed a war-time united front with U.S. encouragement, against the invading Japanese.

He spoke of the bitterness, invective and conflict that followed, including bloody battles between Chinese and American forces in the Korean War, and later a proxy war in Vietnam, only as "a period of unpleasantness between us for 30 years."

Due to the efforts of the two governments and their peoples, normal relations have at last been restored, Teng added. "Sino-U.S. relations have reached a new beginning, and the world situation is at a new turning point."

In brief remarks at a State Department luncheon and in his dinner toast last night, Teng spoke of the global impact of the changed relations between China and the United States. "The interests of our peoples and of world peace require that we view our bilateral relations in the context of the overall international situation and with a long-term strategic perspective," he said.

Asked by reporters if the United States agree with China about the nature of the Soviet threat, Teng responded, "I think both of us have such an understanding." He did not spell out what such an understanding or agreement might be.

At nearly 11 p.m., some 13 hours after he began a nonstop day of ceremony, substantive conversation and official meals and entertainment, Teng made his final speech of the day on the stage of the Kennedy Center Opera House.

With his wife, Cho Lin, and President and Mrs. Carter standing by, the 74-year-old Chinese leader, twice purged and twice returned to power in the government and party, paid tribute to art and culture as a factor in better international understanding. He announced that the Boston Symphony Orchestra will visit China this March to initiate a new cultural exchange program.

Teng is scheduled to have his final substantive meeting with Carter at the White House this morning, followed by a luncheon with the Senate Foreign Relations Committee and a late afternoon meeting with the House International Relations Committee.

The Chinese leader is to attend two receptions in his honor, at the Washington Hilton and the East Wing of the National Gallery of Art, before ending another long day of reconciliation and salesmanship.