Former Prince George's County poilice chief John W. Rhoads, who resigned from the police force a year ago on medical disability, says he is now interested in rejoining county government as a replacement for outgoing county member Francis B. Francois.

Rhoads said yesterday that he has decided to seek appointment to the part-time $24,000-a-year job that will become vacant Sept. 5 as a result of Francois' unexpected decision to quit county government after 18 years and join a national transportation lobbying group.

Francois' resignation annoucement two weeks ago left many political aspirants in the county scrambling to replace the 46-year-old Bowie Democrat on the 11-member council, with Rhoads the most prominent. Francois' successor will be picked from his party by the remaining members of the council.

Rhoads, 44, left his police job in July 1979 with a tax-free $29,700 medical disability pension after presiding over the police during a traumatic four-year period. It was a time of high racial tension in Prince George's County, intensified by several incidents involveing the largely white police force and the county's growing black community.

Rhoads was responsible for implementing strick rules for the department governing the use of force by county officers. While the new rules resulted in a substantial drop in brutality complaints, they also led to a much-publicized no-confidence vote against Rhoads by the rank-and-file officers.

Rhoads retired not long after many police officers walked off the job in May 1979 to protest verdicts in the case of Terrence Johnson, a black youth who shot and killed two county officers. He said he was retiring because an old back injury had begun to act up, making it impossible for him to continue his job. In addition he had told friends privately that he had "simply had it" as police chief.

Since retiring, Rhoads was augmented his pension with part-time jobs as a business lobbyist, police union consultant and public school teacher. He also applied for a law enforcement job in Florida but withdrew his application after county council members accused him of trying to take advantage of the medical disability pension system.

Last week Rhoads said he was intrested in filling the remaining two years of Francois' term, though he was not planning a career on the council. "I'd just like to follow in his footstesp. I've spent a number of years in government and I would like to continue the job [that Francois began]," Rhoads said. He said he would not expect to give up his county pension if he is chosen by the all-Democratic council to complete Francois' term.

Rhoads' annoucement was expected by many county Democrats, who had mentioned the former police chief, Democratic state Del. Charles J. Ryan school board member A. James Golato and former Bowie Mayor Bill Wildman as candidates for Francois' slot.

While many other names have been suggested -- including Hyattsville mayor Tom Bass -- it is expected that Francois' successor will come from his hometown of Bowie, where Rhoads has lived for the last 17 years.

The main stumbling block to a Rhoads appointment, as far as many council members are concerned, is his disability pension. Said one council member: "John Rhoads would be an attractive candidate, but it would be politically impossible for us to vote for him while he is getting a disability from the county."