For the first time in 18 months the flood of refugees from Vietnam has stopped pouring into Southeast China, indicatpolicy but still leaving Peking with at least 250,000 displaced persons to care for.

At this fishing village 75 miles from Vietnam, only one boat with 200 refugees has arrived in the last two months and no one in that time has crossed into China's Guangxi region by land, Chinese officials told the first group of U.S. journalists allowed to visit here.

The tour of this refugee camp was organized by the Chinese Foreign Ministry fo U.S. journalists who covered Vice President Mondale's trip to China last week. The tour reflects Peking's interest in dramatizing the magnitude of its refugee problems.

Although other Southeast Asian nations have had more publicity about their refugee plight, China has received more refugees -- an estimated 251,000 -- from Vietnam than any other nation, including the United States, which now has about 220,000. Peking also is interested in enhancing its image among ethnic Chinese around the world by showing itself actively involved in helping refugees who are almost all ethnic Chinese themselves.

Officials also disclosed that China has for the first time asked the United Nations for funds to help settle the refugeees who now number 96,049 in the Guangxi Xhuang autonomous region alone.

"There really aren't many people like us left in my part of Vietnam," said Zheng Yingho, a 54-year-old fisherman, during an interview on the tiny boat he lives in here. Chinese officials say Hanoi apparently has tightened its borders and stopped policies that forced ethnic Chinese to migrate such as threatening to send them to relocation centers if they did not leave Vietnam.

Chinese officials say that only about 12 refugees here have applied so far to leave to join relatives in other countries, about half of those 12 wanting to go to the United Sates. One refugee here, Trounh Tri Khuan, said her mother lives in New Carrolton, Md., and she hopes to join her but that paper work in the case has been slowed by her lack of a birth certificate. Trounh, 26, arrived here in June 1978.

About 11,000 people, mostly fishing families from North Vietnam, are waiting here for a more permanent port facility promised them by the Chinese. About 7,000 live on their boats and 3,000 in tar-paper shacks that are no worse and in many cases better than the cramped refugee quarters found in Hong Kong, Malaysia and Indonesia.

Through the end of June, 188,979 refugees had crossed into Southeast China from Vietnam, according to Guan Tao, vice chairman of the Guangxi Zhuang region's refugee reception office. A smaller number of refugees up to that period had crossed into neighboring Hunan Province for a total of 251,000 refugees in China, he said. Refugee traffic had been intense until shortly before the Geneva Conference on refugees last July, when Vietnam suspended its policy of forced expulsion.

The fishermen here blame their departure from Vietnam on harassment by Vietnamese police who smashed or took their belongings, sold them boats for exorbitant prices and told them to leave or they would be sent to "new economic zones" inland.

"One policeman said their Soviet advisers told them to drive all Chinese out of Vietnam," said Xian Chengju, a 62-year-old fisherman.

Xian said he left Haiphong on April 13, 1978, and had an uneventful five-day trip across the Tonkin Gulf to reach here. Later his son, his daughter and son-in-law got in a boat and continued on to Hong Kong, but he preferred to stay here.

"We are of the poor people," he said. "I don't know if we could survive in China."

Guan, the Guangxi refugee official, said at a briefing yesterday in the regional capital of Nanning that "those who come to Beihai and do not want to stay in China we give food and water to, in the spirit of humanitarianism, and let them go on their way."

The refugees have settled around a small inlet of the sea where many of the local fishermen already live. The government has built long lines of shacks out of straw mats and tar paper with each family living in a room of about 15-by-7 feet. Bedboards fill most of the space in these with utensils and bedding stacked on the sides and a small cooking shed usually found outside.

Most of the boats were out to sea fishing today, but when they returned, the harbor was a jumble, with the many boats housing refugees, the shacks, the long rows of permanent brick one-story homes for the long-time local fishermen. Sidewalk vendors sell vegetables and eggs, and grimy children run everywhere.

"The refugees have had no adverse effects on our lives," said Luo Zhixiong, 48, a fisherman born in Beihai who is one of the 150,000 permanent residents of this city. He said he had "made no real good friends" among the refugees, but "had several acquaintances."

Refugees and local residents speak roughly the same dialects of Cantonese and enjoy many of the same foods. The only significant difference Luo said, is that "the refugees are superstitious. They all have Buddhist idols in their boats."

Another 11,000 refugees who have entered Guangxi by land are waiting at Dongxing, a Chinese border town just across from the Vietnamese provincial capital of Mong Cai. The Chinese have settled 73,905 people in Guangxi and say they are trying to settle the Dongxing refugees in other provinces, such as Guangdong and Fujian.

The fishermen here have been waiting much longer, 18 months in some cases. A school is now being built and a place has been selected to locate a new fishing village, about seven miles away, as soon as enough boats and fishing equipment can be provided.

The vast majority of the refugees other than the fishermen here have been assigned to work on 41 state farms and forest farms in Guangxi. The farms are run by the state, usually to grow cash crops like pineapples, hemp and tea. Each farm worker is paid a small wage, starting at about $20 to $25 a month.

Six of the 41 state farms in Guangxi were originally set up for overseas Chinese returning from countries like Indonesia that expelled a great number of ethnic Chinese a decade ago. They and other Chinese workers on the state farms, must now move over to give room to the refugees moving into Guangxi as well as other provinces.

"We have only completed 50 percent of the housing for refugees. We still have some problems in the field of education and health," refugee official Guan said.

The Chinese have managed to build several rows of attractive brick homes painted white with blue trim along the Beihai-Nanning road for refugees assigned to a local forest farm. The fishermen here praise the Communist Party for providing rice, clothing and shelter.

Guan said the government spends about $1,100 to settle each refugee. Officials of the U.N. High Commissioner on Refugees visited Beihai and other camps recently, and China took the unusual step of asking that organization for refugee funds.

Peking has shunned international relief offers in the past for disasters like earthquakes, but officials here indicated it was willing to ask for refugee funds because it had recently made its own financial contribution to the fund being collected internationally to help the boat people.