The D.C. Court of Appeals yesterday left intact the sentences of more than 100 persons convicted in the District of sexual assaults, rejecting challenges to the convictions based on the validity of a section of the city's home rule charter.

The case stemmed fron a 1983 Supreme Court decision casting doubt on the procedure by which Congress was then empowered to overturn laws passed by the D.C. City Council. In 1981 the House of Representatives, using that disputed procedure, overturned new criminal statutes covering sexual assault.

Three defendants filed suit, alleging that their convictions or sentences were invalid because of the effect of the Supreme Court decision on the city's home rule authority. The Court of Appeals yesterday rejected those arguments.

"It's a grand slam," said U.S. Attorney Joseph E. diGenova. "Home rule is preserved, Congress' ultimate oversight over the District is preserved and no criminal defendant will benefit from this decision . . . . The net effect is there will be no effect at all."

Congress last year changed the disputed veto procedure to take into account the Supreme Court ruling.

"If the opinon had come out last year, it would have been a very live issue," said acting Corporation Counsel John Suda, the District's chief lawyer. "But in terms of home rule being in jeopardy that was all resolved in October 1984."

The Court of Appeals ruled yesterday that the way in which the House overturned the city's new sexual assault laws in 1981, thus reinstating the old laws, was invalid. But the court rejected arguments of defendants convicted after that House action that they should have stood trial and been sentenced under the new law.

The court ruled that the crimes the defendants committed were violations under both the old and new laws. The court also refused to grant relief to a defendant who argued he might have received a lesser sentence under the new law, if it had been in effect.

"Having to conduct a significant number of resentence hearings would place a significant burden on the administration of justice in the Superior Court," wrote Judge Theodore R. Newman Jr.