More than half the offenders housed in Washington two principal juvenile detention facilities have escaped in recent months, either by running away from the institution or failing to return from home visits or trips.

The administrator of Cedar Knoll and Oak Hill, the District's two facilities in Laurel, Md., said 148 juvenile offenders have escaped since April 1, representing a significant increase over previous years. At Oak Hill, where 150 offenders in serious cases are placed, 55 escapes have been reported since April 1. Cedar Knoll, the medium-security facility that houses 125 offenders, has had 93 escapes in the same period.

There were 46 escapes from Oak Hill in all of 1980, an average of four a month, and 360 from Cedar Knoll, a monthly average of 30.

Since April 1, a total of 117 juveniles who escaped from Cedar Knoll and Oak Hill have been returned, but some of these had escaped before April 1. Some escapees are missing for only a day or two, while others are gone for months, officials said.

Escapes at the juvenile facilities trouble law-enforcement officials because, they say, many of these offenders commit other crimes while they are free, some as serious as murder and armed robbery.

"Some of these kids add to the crime wave and the frustration of the police officers who repeatedly arrest these juveniles only to have them escape again and again," D.C. Police Chief Maurice T. Turner said.

One of every four persons arrested in Washington in the year ending last Sept. 30 in major crimes -- murder, burglary, robbery, rape and assault -- was a juvenile, according to the latest available police figures.

Three months ago, a 17-year-old escape from Cedar Knoll was indicted on 49 criminal counts, including the murders of three elderly residents of oakwood Street SE and a fourth person who lived nearby.

Jimmy L. Wyatt, administrator of the two facilities, said nine juveniles tried to escape from Oak Hill Tuesday, and six succeeded.

"That is atypical," Wyatt said. It was the largest number since nine juveniles escaped in May.

Wyatt said one reason for the increased number of escapes has been libralized ground privileges at Oak Hill and the expanded placement of juveniles in programs outside the facilities.

Thirty-three of the 55 escapes from Oak Hill occurred when the juveniles failed to return from home visits or trips outside the facility, he said. Oak Hill has a perimeter fence about 12 feet high. There is an unarmed guard posted at the main gate and another unarmed guard patrols the fence in a car during the day and evening hours.

Of the 93 escapes at Cedar Knoll, 57 have occurred from the grounds and the other 36 were youths who failed to return from home visits or trips, Wyatt said. Cedar Knoll does not have a fence and is surrounded by woods.

Wyatt also pointed to a staff shortage as a reason for the increase in escapes. He said that there are 12 vacancies among 123 authorized positions at Oak Hill, and 15 among 135 at Cedar Knoll.

Wyatt said juveniles housed at the facilities "are very much aware of the staffing problem" and "make their escape attempts when we have fewer staff."