Oscar E. Kendall, who seduced women throughout the U.S. by claiming that he was high fashion photographer Richard Avedon, admitted guilt yesterday to four crimes in four cities in exchange for the dismissal of 17 other charges pending against him across the country.

In an unusual plea bargain agreement with the U.S. attorney's office here, Kendall pleaded guilty in D.C. Superior Court to assault with intent to commit rape and agreed to drop two rape, 10 grand larceny and five attempted fraud charges pending against Kendall, according the plea bargain agreement filed in Superior Court.

Police investigators contended that the tall, baldish Kendall, 34, traveled from city to city, soliciting women in shopping malls and singles bars with praise for their beauty and grace and promises of the glamor of fashion modeling that he - as RIcard Avedon - could give them.

The women later complained to police that Kendall swindled them of their money and, in some cases, sexually assaulted them. The trail ended in Washington last September, when Kendall, back in Washington for the first time in three years, was recognized by a bartender in a singles night spot from a photograph that appeared in the Washington Post that day.

At a hearing before Judge H. Carl Moultrie I yesterday, Kendall, who has been described by police as a "smooth talker," appeared somwewhat nervous and spoke in a low, almost inaudible voice when he was questioned by Moultrie about the plea agreement.

As a result of his guilty plea to the assault charge here, Kendall faces a maximum prison term of 22 1/2 years in prison, according to the agreement. The charge normally carries a penalty of up to 15 years in jail, but because Kendall was convicted of the same charge in Florida in 1968, he is subject to the additional prison term under D.C. law.

The grand larceny charges in Miami and Detroit each carry a penalty of five years in prison. As part of yesterday's agreement, however, the Miami prosecutor has agreed to recommend that Kendall's sentence in that case run concurrently with any prison time imposed in the Washington case. The Detroit prosecutor has indicated that Kendall's sentence there must by law run concurrently with his Washington sentence.

In San Mateo, Calif., however, where Kendall has agreed to plead guilty to a charge of grand theft, the prosecutor there has reserved the right to ask the court to sentence Kendall to a prison term to be served consecutively to any sentence imposed in Washington. The grand theft charge is punishable by a maximum of five years in prison.

If Kendall is sentenced to maximum prison terms in each case, he would technically be eligible for parole on the Washington charge in about seven years and would then have to serve five additional years in prison on the California charge, subject to parole provisions of that state.

At the hearing yesterday, Kendall entered what is known in legal circles as an "Alford plea," which takes its name from a 1970 U.S. Supreme Court case, Alford v. North Carolina. The plea means that while Kendall contends that he is innocent of the charge, he has decided to plead guilty because of the strength of government's evidence against him and the likelihood that he would be convicted by a jury.

Kendall's attorney, Leroy nesbitt, told Judge Moultrie yesterday that if the Washinton case had gone to trial, Kendall would have contended in his defense that the victim consented to his sexual advances.

Assistant U.S. Attorney John P. Hume told Moultrie that the government could prove that Kendall met the woman in a Northwest Washington bar, that he took her for coffee and then accompanied her to the door of her room at a Hotel.

The woman allowed Kendall to use the telephone, on the promise that he would stay only five minutes, Hume said he could prove. But Dendall instead forced the woman to disrobe and raped her, Hume said the government's evidence would show. When Kendall later fell asleep, the woman ran for help, Hume told Moultrie. According to police accounts of the incident, when the woman returned to the room, Kendall was gone.

Hume said a thumb and palm print in the room and other pieces of physical evidence tied Kendall to the incident, which occured on Aug. 9, 1974. Three years later, identified Kendall as her assailant at a police lineup, Hume said.

After accepting Kendall's guilty plea, Moultrie scheduled sentencing on the Washington charge for May 5.

At the time of Kendall's arrest here last September, police said he had previous convictions for forgery, assault and transporting stolen property, and committed various parole violations. He had served nine years in prison and last May was released from a California jail where he had served 2 1/2 years for grand theft, police said at that time.

D.C. police detective Thomas Kelly, who has closely followed the case since 1974, said at the time of Kendall's arrest that Kendall is divorced, has a daughter and that his mother lives in Queen Creek, Ariz.

Kendall is being held in the D.C. jail, without bond, Pending his sentencing here.