NEW YORK (AP) _ More than 800 Chinese students studying in the United States have signed their names to an open letter opposing China's policy to sharply reduce the number of students abroad, a student organizer said today.

''We have had an overwhelming response from fellow students across the country,'' said Pei Minxin, a 30-year-old doctoral candidate at Harvard University. ''It's been a mixture of shock, anger and action.''

At a meeting late Wednesday at the Massachusetts Institute of Technology, about 300 Chinese students shouted down a Chinese consular official who came from New York to explain the policy, said two Chinese sources speaking on condition of anonymity.

''It was democracy in action,'' one source said.

The letter, which appeared in Chinese-language newspapers across the United States on Tuesday and Wednesday, said the policy would hurt China's drive to modernize its economy.

''The recent unreasonable changes in the policies on overseas study are fundamentally in conflict with the declared national policy of reform and open door,'' read the letter, which was translated by The Associated Press.

The policy will also force many Chinese students in America to return to China before obtaining their degrees, the letter said.

The document was accompanied by the names and phone numbers of 21 Chinese students and a request for student supporters to add their names to the list. By early today, more than 800 students had done so, Pei said.

Currently, about 40,000 Chinese students are studying abroad, 27,000 of them in the United States. Last year, 8,000 students came to the United States from the People's Republic of China.

Under the new policy, only 600 Chinese would be sent to America, according to Chinese news reports, an official document seen in New York and Chinese students who quoted government officials.

Time limits on students studying abroad would also be imposed, said the document, which was obtained from Chinese sources. That rule could be particularly difficult for many Chinese, who need time to master a foreign language before studying their specialty.

A spokesman at China's embassy in Washington acknowledged Wednesday that fewer students would be sent abroad, but denied there has been a policy change.

At the MIT meeting, the unidentified consular official confirmed that a time limit had been placed on studies, the sources said. ''He said we have two years to do a masters (degree) and four or five to get our Ph.D.,'' one source said.

The policy is the result of a struggle between Chinese Premier Li Peng and Communist Party Chairman Zhao Ziyang, said Boston University history professor Merle Goldman.

Zhao backs an ''open-door policy'' and increasingly liberal economic reform. Li, a Soviet-educated engineer, wants to limit China's contact with the West, and is concerned that Chinese students studying abroad are becoming too Westernized, Ms. Goldman said.

When Chinese students come home, she said, ''they are already infected by the political values of the United States. They absorb Western political ideas and that could be troublesome for the Chinese state.''

At MIT, the official told students that China has felt the need for more control over its students since January 1987, when more than 1,000 Chinese nationals in America signed an open letter to Beijing opposing conservative policies in their homeland, the sources said.

At that point a Chinese student jumped up and yelled, ''Control? What do you mean by control. What kind of word is that?'' the sources said.

Zhang Longxi, a 40-year-old doctoral candidate at Harvard, said he did not see the letter as a political statement.

''It is a bread-and-butter issue for me,'' he said. ''I need time to study comparative literature.''

''We are only asking that the right to study and complete our degrees be restored to us,'' Pei said.