Soong Ching-ling, 90, the widow of modern China's founding father, Sun Yat-sen, and an important historical figure who remained near the center of power in China for nearly 65 years, died here tonight, official news reports said.

Although her official name was Soong Ching-ling, she was called Madame Sun and she was known as the matriarch of pre-communist China. She died at her home in the presence of her relatives who, like the rest of the nation, have anxiously stood by as her health gradually deteriorated over the last two weeks. Doctors listed lymphatic leukemia as the cause of death.

Officials immediately announced that a state funeral will be held for Madame Sun, who was named China's honorary head of state and given a dramatic deathbed conversion to the Communist Party after her illness became serious May 16. Memorial services also have been planned for the Great Hall of the People.

Capitalizing on Madame Sun's tremendous popularity, China's ruling Communist Party has devoted extraordinary attention to her final days. Leaders have lined up at her bedside. Newspapers extolled her. Medical bulletins were issued every day, a practice not used even when Mao Tsetung was dying in 1976.

The fact that she was the wife of Sun Yat-sen, the first president of Republican China after the overthrow of the Manchu Dynasty in 1911, assured her of lasting political influence in Communist China even though she never joined the party until this month. She held several high government posts under the communists, including most recently that of vice chairman of the Chinese parliament.

Her own family backgrounmd was extraordinary and her marriage to Sun in 1915 added luster to it. She was one of the famous Soong sisters whose husbands shaped the course of modern Chinese history. Her younger sister, Soong Mei-ling, married Generalissimo Chiang Kai-shek, while her older sister married prominent financier and Nationalist Chinese politician H. H. Kung.

Madame Sun's own political leanings were more leftist than those of her sisters. After Sun's death in 1925, she openly sided with the left wing of the Kuomingtang (Nationalist) Party, which her husband had founded, and backed the Communist regime after its takeover in 1949.

Madame Sun was born into a wealthy Christian family in Shanghai, the second daughter of American-educated businessman Charlie Soong. Like the children of many rich families in China at the time, she was sent to the United States to study and graduated from Wesleyan College for Women in Macon, Ga.

Through the years she retained a fondness for Americans, and when Jimmy Carter was president she told a reporter that she was looking forward to meeting her "fellow Georgians." For years she regularly received copies of the Sunday New York Times and often gave speeches in English.

After receiving her degree at Wesleyan in 1913, she headed back to China, stopping in Tokyo, where she met Sun. He was 25 years her senior and already married. She offered her help to him during the brief stopover and they were married two years later.

Acting as Sun's secretary, she became deeply involved in his revolutionary activities and served as his English-language translator. In 1923, she participated in negotiations with the Soviet revolutionary official Michael Borodin that led to a reorganization of the Kuomingtang and a united front with the Communist Party.

Returning to Shanghai after her husband's death, Madame Sun became active in the student movement and began verbally attacking the right wing of the Kuomingtang led by her brother-in-law, Chiang Kai-Shek, who was fighting the leftists for control of the party.

Capitalizing on her prestige as Sun's widow, she was the only leftist Kuomingtang figure at the time who dared to oppose Chiang, criticizing him for his "antiquated theory" of first suppressing the Communists in China before turning his army against Japanese troops that invaded the country in 1931.

During China's war with Japan, she organized hospitals for wounded Soldiers, wrote pamphlets urging resistance to the Japanese and raised funds from overseas Chinese to finance China's war effort.

At the same time, Madame Sun kept up her political work, criticizing Chiang in her own articles and interviews with foreign correspondents. She repeatedly warned American diplomats in China about the repressive nature of Chiang's regime and repeated her charges of "undemocratic conditions" in China when U.S. Vice President Henry A. Wallace visited on a fact-finding mission in 1944.

While holding official posts in the Kuomingtang after the war, she supported the communist calls for a coaliton government and urged the United States to stop aiding Chiang's army, maintaining that military assistance contributed to civil war in China.

After the People's Republic of China was officially inaugurated by Mao Tse-tung on Oct. 1, 1949, she was chosen as one of the three noncommunist vice chairmen of the Central People's Government Council, the highest state body at the time, which passed almost all the important statutes in Communist China during the early years of the regime.

Madame Sun served in several other high posts, including the chairmanship of the Sino-Soviet Friendship Association and the chairmanship of the organization that coordinated relief and welfare programs for regions hit by famine and flooding.

Despite her bourgeois family background -- millions of others and similar backgrounds have been targets for radical attacks during the past 32 years -- Madame Sun generally managed to remain immune to criticism. During the Cultural Revolution, Red Guards stormed her home in Shainghai. dBut Premier Chou En-Lai quickly jumped to her defense and scolded the young radicals.

In recent years, poor health has limited her activities, although she has appeared in public from time to time and maintained her nominal position as vice chairman of the National People's Congress. The job includes receiving the credentials of foreign diplomats when they arrive in Peking.

Madame Sun made a rare public appearance on May 8 when she received an honorary degree from Canada's Victoria University. Although she was confined to a wheelchair and obviously was in frail condition, she delivered a speech at the ceremony in which she strongly criticised the Soviet Union.