Government prosecutors, urging a federal judge to deny bond to John W. Hinckley Jr., said yesterday that Hinckley's own safety could be in jeopardy if he were released from custody before his trial on charges that he attempted to assassinate President Reagan.

Justice Department spokesman Thomas P. DeCair confirmed yesterday that several threats have been made on Hinckley's life since his arrest last March 30.

Hinckley is being held at the Army stockade at Fort Meade, Md., and is isolated from other prisoners there. Hinckley pleaded innocent to all charges against him at a hearing in U.S. District Court last Friday -- a hearing that was conducted under extremely tight security procedures.

U.S. District Judge Barrington D. Parker is expected to consider Hinckley's request for bond today. Hinckley has waived his right to attend that hearing and will not appear in court.

In court papers filed yesterday, prosecutors also contended that the evidence of Hinckley's guilt is so "overwhelming" that Hinckley would have an "overbearing motive to flee" if he were released on bond.

The government also contended that sufficient evidence has been raised about Hinckley's mental state, both by prosecution and defense lawyers, to raise a question that he is a suitable candidate for release on bond.

Under federal law, defendants are entitled to bond unless there is a risk that they will flee to avoid prosecution.

Assistant U.S. Attorney Roger M. Adelman said in court papers yesterday that the government believes that because of the "extraordinary" circumstances of the Hinckley case that no money bond or other conditions for release could adequately ensure that Hinckley would show up in court.

Hinckley, 26, an unemployed drifter from a wealthy Denver family, has led a "rootless life" during the last fews years, traveling around the country using aliases and concealing his whereabouts from his family, the government said.

If Hinckley's parents were to post a money bond for him, the government said, he could still flee from prosecution since he would have no financial stake in the money that would be forfeited.

Hinckley's attorneys argued that Hinckley's release would guarantee that he had complete access to his lawyers and defense psychiatrists for the preparation of his defense.