The Senate Judiciary Committee approved a long-debated overhaul of the criminal code yesterday. It would make dramatic changes in federal sentencing and parole.

In a separate but related action, a new death penalty statute was approved covering treason and espionage, and applying also to murder when associated with aircraft hijacking and federal kidnaping or rape violations. Supporters of the code revision fought off efforts to add the death penalty statute as a rider, saying it would have complicated their debate.

The massive code revision, comprising laws that Congress has scattered over the books in 200 years of legistive activity, would make substantive changes in statues involving civil rights, elections, rape and marijuana, and lesser alterations in hundreds of other areas.

A similar bill was passed by the Senate last year but died in the House Judiciary Committee. Difference between House and Senate have been ironed out this year, Senate sources believe, giving the revision a much greater chance of enactment.

Yesterday's 13-to-1 vote in the Senate panel was especially significant for its chairman, Edward M. Kennedy (D-Mass.), chief backer of the revision.The presidential candidate has been criticized as unable to shepherd important legislation through his committee.

But the separate vote on the death penalty measure, which passed 7 to 4 with Kennedy voting no, evoked criticism from the American Civil Liberties Union that the chairman had made "a politicial deal" that completely surprised foes of the death penlty. Kennedy aide Ken Feinberg denied that there was any agreement to vote on the death penalties in return for approval of the code revision.

The code revision would eliminate parole in the federal penal system. It also would remove most of the discretion now exercised by federal judges in sentencing, substituting a system of relatively uniform sentences of determinate length that could be reduced only under special circumstances.

Currently, two persons convicted of identical crimes may be sentenced by two different judges to vastly different sentences. And those sentences may be served in vastly different proportions because of varying parole policies.

Other provisions in the bill would:

Eliminate jail terms for simple possession of marijuana while increasing the penalties for marijuana trafficking.

Expand the Civil Rights Act of 1968 to include sex discrimination as well as racial, religious and ethnic discrimination.

Change federal rape laws to eliminate the need for extra cooroboration of the victim's testimony.

Create a new prohibition on sabotage of political campaigns.

Tighten laws directed at organized crime and racketeering.

Create a general five-year statute of limitations for most felonies and misdemanors instead of different statutes for different crimes.

Allow prosecution as adults of 16-year-olds for certain serious crimes; the current age in federal law is 18.

The bill, if it becomes law, would apply only to federal offenses, a small proportion of the country's court docket. The majority of crimes are prosecuted under state laws. Traditionally, however, the states have tended to follow the federal lead in many areas and changes in federal law are likely to result in similar changes in many state laws.

Criminal code revision has been debated since the administration of Lyndon B. Johnson, when a special commission first spotlighted the chaotic state of federal law.

Much of the revision is designed to rearrange the laws, rather than significantly change them, and to eliminate statutes considered obsolete.