Steve Stone, in only his second start since May 16, shut out Seattle for 7 1/3 innings tonight to help the struggling Baltimore Orioles conquer the Mariners, 1-0, in a matchup of two-hitters.

Stone showed no evidence of the tendinitis that had plagued him since May, and afterward said, "My command of the ball was as good as in a long time -- since last year (when he was 25-7)." This welcome victory was just No. 3 of 1981.

Asked if he was "back," Stone said, "I'm in the starting rotation and I'm pitching well. What difference does it make if I'm back? I'm building my endurance and I don't feel I can give nine strong innings. Maybe next time. Those 98 pitches tonight seemed like 198."

Even before Stone started throwing zeroes, there was good news from the mound corps. An electromyogram on Jim Palmer's sore right shoulder found no new nerve damage and a shot of cortisone was followed by the news that Palmer would face Oakland here Thursday. Mike Flanagan, who missed his turn Monday with tenderness in his left elbow and forearm, felt no pain today and will go against the A's Friday.

For an extra fillip, there was the relief effort of Tippy Martinez, who replaced Stone after a one-out walk to Jerry Narron in the eighth. Martinez needed one pitch to induce Gary Gray to ground into a double play. In the ninth, Martinez struck out Julio Cruz on three no-swing strikes, got Bruce Bochte on a first-pitch comebacker and fanned Tom Paciorek on four pitches.

Seattle right-hander Glenn Abbott was the tough-luck loser. The Orioles' only run came in the fourth, as Rich Dauer opened the bottom of the inning with a double that struck the outside of the bag at third and went on down the line. Dauer moved around on grounders by Ken Singleton and Eddie Murray, both to backed-up second baseman Cruz.

Baltimore had only three other base runners. Al Bumbry walked and was out stealing in the first, then Singleton walked with two out and was stranded. Bumbry singled and stole second with one out in the sixth but went no farther.

The hits off Stone were sharp singles by Cruz in the fourth and by Terry Bulling in the sixth. Stone walked four, but no Seattle runner reached second base safely.

Cruz, who entered the game with 37 steals in 40 attempts, was nailed twice by catcher Rick Dempsey. It was the first double defeat to one catcher in Cruz's career, although he was caught leaning twice by Kansas City pitcher Andy Hassler in 1978.

In the fourth, Cruz took off on a breaking ball and should have reached second with ease. However, Cruz, who has been known to stop on a batted ball to see if it is fair or foul, slowed 20 feet from the bag, because "I thought it was a hit and run and I wanted to see if he made contact."

The two outs were Dempsey's first successes of the second season. He had caught 12 of the first 13, then had seen 13 straight runners beat him.

"Steve held them fairly close and gave me an opportunity to throw them out," Dempsey said. "We haven't been holding the runners and my percentage has been going way down."

Second baseman Dauer helped Stone with two outstanding backhanded stops and throws for outs. He handled Richie Zisk's fourth-inning grounder on the shortstop side of second, racing to his right when Paciorek broke from first on a run and hit.

"That kind of defensive support is the only way you can win a 1-0 game," Stone said.