A federal judge here allowed four members of the Revolutionary Communist Part to plead guilty yesterday to harassing the Chinese chancery last January, even though government prosecutors opposed the guilty pleas and said the men should stand trial on a more serious charge.

Over the objections of U.S. Attorney Earl J. Silbert and one of his assistants, William H. Collins Jr., U.S. District Judge June L. Green said that acceptance of the guilty pleas was justified as a fair disposition of the case and to save time and money to pay jurors.

The four revolutionaries - James J. Nelson, Curtis J. Mohn, James E. Loudermilk and Mark W. Jackson - are supporters of the late Chinese Communist Party chairman, Mao Tse-tung, and participated in a brief, violent attack on the Chinese chancery Jan. 24.

Lead fishing weights were thrown through the windows of the chancery at 2300 Connecticut Ave. NW and paint was splashed across the front o the building to protest the visit a few days later of Chinese Vice Premier Teng Hsiao-ping.

The four men now face up to six months in jail and fines to $500. But the prosecutors argued that they should either stand trial on a charge that they destroyed foreign property or plead guilty to that charge, an offense that carries up to a five-year prison term and a $5,000 fine.

Collins said the government would probably appeal Green's ruling.

From the start, the government's handling of the incident has presented problems for Collins, the courtroom prosecutor in the case. Green earlier dismissed charges that the protesters assaulted a Secret Service officer during the attack on the chancery after learning that the Secret Service had routinely erased a tape recording and burned interview notes about the incident.