John J. Curry, a former business manager of Southeastern University in the District, pleaded guilty yesterday to taking part in a scheme to defraud the university by placing about $500,000 in inflated contracts with a business associate and receiving $80,000 in kickbacks.

Among the contracts, Curry acknowledged here in U.S. District Court, was a pact for cleaning services that cost the university $13,292 a month for work that a student cleaning crew was paid $4,000 monthly to perform.

In a court statement, Assistant U.S. Attorney Steven C. Tabackman said the contracts, made with companies controlled by Gerald Schall, formerly of Upperville, Va., also overcharged the university for books, office furniture and maintenance supplies.

Curry, 53, of Potomac, pleaded guilty to interstate transportation of property obtained by fraud and income tax evasion, charges that carry sentences of up to 15 years in prison and $20,000 in fines. His wife, Annette Florio Curry, who was an incorporator of the firm that received the cleaning contract, pleaded guilty to subscribing to a false income tax return, That charge carries a maximum penalty of three years in prison and a $5,000 fine. U.S. District Judge John Garrett Penn set sentencing for Sept. 11.

Schall, who had been convicted of mail fraud in 1974 in connection with a home improvement scheme in Pittsburgh, currently is in federal prison. His probation was revoked by a judge in late March.

According to information filed in court here yesterday, the fraud scheme at Southeastern University continued from early 1982 to September 1983, when it was discovered by university auditors and Curry was fired.

In 1981 the university fired another business manager, Joyce Jobe-Balfour, whom the trustees accused of misappropriating funds. Jobe-Balfour filed suit against the university in connection with the firing and was awarded $601,000 by a Superior Court jury.

According to depositions from school officials filed in that trial, an audit report revealed that university funds had been channeled to the Culinary School of Washington, of which the then-president of the university, Barkev Kiberian, was a trustee. Kiberian was forced to resign after the audit report, the depositions said, but has not been charged with criminal wrongdoing.

Yesterday U.S. Attorney Joseph E. diGenova praised the current president of Southeastern, Robert Higgins, for "fully cooperating with our investigations."

"He is doing everything humanly possible to clean house," diGenova said.

The university, which enrolls about 1,000 students mainly in business courses taught at night, was founded by the YMCA in 1879. It is located at 501 I St. SW, and operates as an independent nonprofit corporation.

Yesterday Tabackman said in court that the government also had evidence that Curry arranged for a contract for security guards at Southeastern with a firm that he and his wife formed with Jack Vincent, a D.C. police sergeant. The school spent $103,000 for the firm's services in 1982 and 1983, Tabackman said, without Curry disclosing his financial interest.

Tabackman said Vincent has been reprimanded by police for holding a second job, but said he was granted immunity from prosecution in return for promising to testify against the Currys.