William H. Simmons won easy reelection Monday night as president of the Washington Teachers Union, beating his only opponent by a vote of 553 to 338.

Despite Simons' wide margin of victory, it was a bitterly fought campaign that often pitted teacher against teacher in acrimonious disputes. It was Simons' stiffest challenge yet from Ballou High School teacher James D. Ricks, who had failed twice before to unseat Simons.

Ricks had the support of many teachers disgruntled over last year's layoffs of 400 teachers and by the 1979 teachers' strike.

Simons, who has been the only president in the union's 17-year history, will again be the chief negotiator for the union when new contract talks begin next month. The teachers will be able to bargain for salaries this year for the first time since the D.C. City Council last year granted all city employes bargaining authority for salaries.

"How sweet it is," he said yesterday about his reelection, repeating a phrase he used at union rallies during the 1979 strike. "I am certainly pleased that the teachers used their good judgment and returned me to office."

As the ballots were taken out of locked boxes and counted last night at the Executives House Hotel in Northwest, Ricks supporters accused the union elections committee of various election irregularities.

Mary Wimbush, Ricks' campaign manager, said the votes of some Ricks poll watchers had unjustly been challenged because these teachers had voted at the schools where they were watching the balloting, rather than the schools where they teach.

Wimbush also complained that some elections committee officials had refused to let certain Ricks poll watchers ride with the ballot boxes to the hotel.

Harold Fisher, Simons' executive assistant, said the votes of some Simons poll watchers had been challenged as well. He said some elections committee officials apparently had not received a list of names of poll watchers who were exempted from voting at the schools where they teach.

Mary Ross, the elections committee chairperson, said she knew of no instance where Ricks' poll watchers were unable to ride the ballot boxes to the counting place.

The entire Simons slate won reelection to various union posts, including at-large representatives to the elementary, junior, and senior high schools and the board of trustees. Jimmie D. Jackson, director of the D.C. Teachers Center, will again serve as the general vice president.