For three years, President Reagan has tried unsuccessfully to persuade Congress to abolish the Justice Department's Office of Juvenile Justice and Delinquency Prevention. Now some critics fear that his new choice to head the office is accomplishing the same goal indirectly--by shifting its emphasis from prevention to punishment.

With the changes have come charges from employes, congressional staff members and juvenile-justice experts that acting director Alfred Regnery is violating the Juvenile Justice Act and has cut funding to a number of programs named on a political "hit list."

Regnery, whose Senate confirmation hearing is scheduled for Wednesday, says freely that he intends to change the program's previous emphasis on delinquency prevention, children's rights, and youth advocacy.

"Yes, the emphasis is being changed--away from . . . status offender problems and directed toward more serious crime . . . . The direction will be more Justice Department-oriented and less Health and Human Services-oriented," said Regnery, a former official of the conservative Young Americans for Freedom and aide to Sen. Paul Laxalt (R-Nev.).

"We have done a good deal of work with delinquency prevention. It's a nice idea, but no one has really been able to figure out how to do it. We've spent tens, maybe hundreds of millions of dollars on delinquency prevention programs. But none are in the least bit effective.

"My emphasis will be away from spending money on delinquency prevention programs that don't work and toward dealing . . . with kids who have gotten into trouble."

Gordon Raley, staff director of the House subcommittee on human resources which has oversight responsibility over Regnery's office, said the subcommittee is considering asking the General Accounting Office to investigate the program.

Sen. Arlen Specter (R-Pa.), chairman of the Judiciary subcommittee on juvenile justice, also has begun to look into Regnery's changes of direction.

"The main concern has to do with whether Mr. Regnery will carry out congressional intent," said Raley. "He says he wants no more prevention programs, but prevention is mentioned 94 times in the law.

"He has decided--based on several weeks of experience in the juvenile justice field--that it's in the best interests of the country not to fund delinquency prevention programs. We have a very direct disagreement there . . . . Too much of our past efforts were based on working with kids after they were already adjudicated delinquent."

Raley said there have been "allegations of hit lists both inside the office and out."

The subcommittee has obtained one such list in the form of a memo from Arne Schoeler, an associate director of the National Council of Juvenile and Family Court Judges, a professional association of more than 3,000 juvenile-court judges. The group has since disavowed it.

The memo was sent to two judges who serve on the National Advisory Council to Regnery's program: John R. Milligan, a judge in Ohio, and Edward V. Healey Jr., associate justice of the Family Court of Rhode Island.

The memo, written less than a month before Regnery took over the office, said his staff was preparing to award funding grants to "exactly the wrong people." It named a number of persons and organizations and warned against awarding the grants "without reviewing these recipients first.

"That's like a farmer bunking the traveling salesman in with his daughters and then giving the ground rules the next morning," it added.

Milligan sent the memo to three other members of the National Advisory Committee with the notation: "The enclosed deserves our attention. If the bureaucracy executes grants to the National Youth Work Alliance and Ted Rubin (an ultraliberal former Denver judge . . . ), the thinking of most of us continues to be frustrated by the anti-system people . . . . "

Funding to a number of the groups and individuals named in the memo has been reduced or eliminated since Regnery took over his current position. Most appear to involve counseling and jobs programs for young people or training programs for prosecutors and other court personnel.

None of the individuals contacted by The Washington Post would comment on the record, all saying that they depend on federal funding of one kind or another.

Milligan could not be reached for comment. Healey said he completely disapproves of the memo and went on to praise some of those named in it.

"That was an expression of a single individual, a very unfortunate expression," he said. "I totally disavow it."

Healey said he does not know whether the memo led to the funding cuts because the National Advisory Commission is not involved in grant decisions.

"I know it reached the department," he said. "Whether the memo is the cause of the cuts, or whether they thought they should go in a different direction, I don't know . . . . Only Regnery and the staff could tell you."

Regnery said through a spokesman that he has never seen the memo.

Almost no one disputes that the juvenile justice program, which now has an annual budget of $70 million, has been a success since it began in 1974. Its emphasis has been in the areas of delinquency prevention, counseling, job programs, special training for judges and police, and efforts to keep institutionalized children separate from adults.

According to Raley, 50 percent of all serious violent crimes were committed by persons under 18 years when the program began. The figure is now 35 percent, he said.

Regnery claims the program has finished what it set out to do.

"The mission of the office was reasonably well accomplished . . . ," he said. "It's simply a program that isn't necessary . . . . It doesn't really fit into the Department of Justice."

But Regnery insists he was not sent in by the Reagan administration to destroy the program.

"That's absurd," he said. "Nobody has given me any instructions on what to do. I know the administration's general program on crime issues. My own mission is to make the program work as well as possible."

Regnery said he has not cut grants but merely refused to renew certain programs as they expire. One was the Children's Legal Rights Information and Training Program, which published newsletters and books dealing with children's rights, training and juvenile rehabilitation programs. Another was a small juvenile-defense program run by the National Legal Aid and Defender Association

Regnery has shifted $2 million to a program stressing tougher penalities for violent offenders, particularly youth, in big cities. He is considering a program to single out juvenile drug offenders for stiffer penalties.

Regnery also may spend $9 million to participate in a computerized program among police forces to identify children's bodies and find patterns in murders of young people in different jurisdictions. An estimated 5,000 to 8,000 unidentified children's bodies are found each year.

Several juvenile-justice specialists, who asked not to be identified, said such programs are valid but don't come under the jurisdiction of the Juvenile Justice Act. The head of one federally supported youth program said:

"The first priority under the act was to help children, rehabilitate children who had gotten on the wrong side of the law, with a lot of emphasis on prevention. But he's taken the approach that the Office of Juvenile Justice is in the business of helping the victim and putting these kids away for as long as necessary.

"The whole emphasis now is on lock the kids up, teach them a lesson, a real hard line approach . . . . This man's going to be very detrimental to the nation's children."

Regnery has no qualms about his approach:

"There is an interesting phenomenon in juvenile justice, a network of people involved in the system . . . . They talk to each other every day. Rumors are rampant. That network has a fear that the conventional wisdom, the traditional orthodoxy, will be challenged . . . . They probably view my position as one where I'm willing to challenge conventional wisdom, and they're right. I think there needs to be a breath of fresh air."