All-star forward Jeff Ruland of the Washington Bullets agreed yesterday to an extension of his contract with the National Basketball Association team.

"I think everybody got what they wanted," he said last night. "So now I can go about my business and can concentrate on playing . . . I'm so relieved it's finally over. It's been so long."

Neither Ruland nor his attorney, Kevin Plunkett, would disclose specifics, but it is believed that the contract was extended for two years and his base salary has at least doubled.

General Manager Bob Ferry of the Bullets was not available for comment last night.

Ruland, 25, had three years left on his five-year contract and would have earned $325,000 this season, $400,000 next season and $450,000 in 1986-87.

"It's not a lifetime extension, not your Magic Johnson type of deal," Plunkett said. "The contract from Jeff's perspective is financially reasonable for a player of all-star caliber last season."

"I just will have more security," Ruland said. "I have a daughter now; I have things like that to consider. Now I have money to stash away for a rainy day."

Ruland, who is 6 feet 10 and weighs 240 pounds, was third in the NBA in rebounding (12.3), sixth in field-goal percentage (.579) and 15th in scoring (22.2) last season. In addition to having more assists (296) than personal fouls (285), he averaged 41 minutes a game for a Bullets team he earlier this week said depends on him "to score 25 points a game, get 15 rebounds, dish out nine assists and sell the popcorn."

Ruland, who developed into a star in his second NBA season, had wanted for more than a year to renegotiate. Last season, the team's owner, Abe Pollin, told him the Bullets would renegotiate during the offseason if he had another good year.

But on the eve of training camp, Ruland said he might not report because he considered negotiations at an impasse after only he had made concessions and said the Bullets had offered "peanuts" for a two-year extension.

Negotiations resumed that night between Plunkett and Ferry, and Ruland reported to training camp the next morning. It then took almost two weeks to complete the deal.

Ruland has grumbled about how much other players, such as Marvin Webster and Bill Cartwright of the New York Knicks, earn. Webster will earn $450,000 base salary this season and Cartwright $600,000. Last year, Len Elmore, a Knicks' reserve, earned $225,000, only $50,000 less than Ruland. Mike Gminski of the New York Nets made $350,000.

Even a reserve forward such as Bob McAdoo of the Los Angeles Lakers had a base salary of $756,000 last season ($878,000 this season).

With the Bullets settling with Ruland, the only apparent remaining contract problem is with Greg Ballard, their starting small forward the past four years. Ballard declined an offer by the team last year in order to test the free-agent market.

But he has not received an offer sheet, and both Ferry and Larry Fleisher, Ballard's attorney, refuse to initiate negotiations.

Fleisher said three weeks ago that he didn't believe the Bullets were interested in Ballard, who has declined comment about his situation. On Wednesday, Coach Gene Shue said, "We need a player like Greg Ballard. He would give us another weapon, and we want as many weapons as we can get."