District and federal officials disclosed a long-awaited, multimillion-dollar plan yesterday that would transfer to the city government full control over the local criminal justice system by 1981.

The plan is but the first specific step in a process that requires Congressional approval. Nevertheless, Mayor Marion Barry described the plan as "an important step in the home-rule process" that began a decade ago when Congress greatly expanded the District's local court system.

The Justice Department, which in the past has objected to turning over prosecutorial authority to the District government, now supports the concept in principle, Barry said.

Barry and other local political leaders have long considered the transfer of authority essential to giving the District full self-government. The White House this year gave its support to the change, but city officials continued to face resistance from Justice Department officials.

One strong opponent was former U.S. Attorney Earl J. Silbert, who has repeatedly contended that the switch would jeopardize the quality of justice in the District. Silbert, who made his objections known to President Carter in his resignation letter last June, argued that the unique federal status of the District demands the resources of a federal prosecutor's office.

According to the plan, the new system would cost an estimated $13 million to $14 million during its first year of operation. This would be paid in full by the federal government.

In the second year, the District government would assume 25 percent of the costs. By 1985 the District government would pay the full costs.

The plan would give the District government authority over all local criminal prosecutions, authority that now rests with the United States Attorney's office for the District of Columbia.

It would also give the mayor the authority to nominate the city's top prosecutor as well as judges of the local trial and appeals courts. The mayor's nominations would be subject to confirmation by the D.C. City Council, according to the plan.

Currently, the president nominates both the U.S. Attorney and the court judges. Federal and local criminal cases are brought by the federal prosecutor's office and less serious, local criminal violations are prosecuted by the D.C. Corporation Counsel's office. That office also handles civil matters involving the local government.

The new plan would establish an Office of the Attorney General for the District of Columbia, with both criminal and civil subdivisions to supervise all local prosecutions and civil cases.

The local attorney general, the chief legal officer, would have "broad supervisory responsibility for law enforcement and criminal justice matters in the District" according to a summay of the plan released yesterday.

The mayor would have the authority to nominate the attorney general to a four-year term, subject to council approval.

The criminal division of the attorney general's office, headed up by an associate attorney general, would control all local criminal prosecutions now handled by the U.S. Attorney's office, according to the plan.

Prosecution of juvenile delinquency cases and serious traffic, tax and city regulation violations now handled by the corporation counsel's office would also be brought under supervision of the criminal division.

An office of district counsel, or associate attorney general for civil and administrative matters, would also be established. That office would have additional authority over some family related matters, such as child abuse and neglect cases.

The draft plan is modeled on the attorney general system used in the states. The proposal for a criminal division of the local attorney general's office closely parallels current operations at the Superior Court division of the U.S. Attorney's office, which now handles local criminal matters.

According to the plan, the D.C. Corporation Counsel's officer would be abolished once the civil division of the Attorney General's office is in operation.

City officials hope to submit transfer legislation to Congress in November. The draft plan is now being circulated to local and federal officials, Congress and members of the local bar for comment.

The plan was released yesterday at a luncheon meeting at the Justice Department attended by Barry, D.C. Corporation Counsel Judith W. Rogers, Chief Judge H. Carl Moultrie I of the D.C. Superior Court, Acting Deputy Attorney General Charles Ruff, members of the White House staff, the city council and others.

Ruff, who has worked closely with city officials on the transfer plans, is expected to be nominated by President Carter to be U.S. Attorney for the District of Columbia.

In that job, Ruff would oversee the dismantling of the federal prosecutor's office insofar as its role in local criminal cases.

The $13 to $14 million cost to the city government for the transfer of jurisdiction represetns salaries for attorneys in the new criminal division, salaries now paid by the federal government through the U.S. Attorney's office and the pricetag for a local marshal service. That service would handle security in the District of Columbia Courthouse, movement of prisoners and other local administrative matters now handled by federal marshals, such as service of subpoenas.