George Graefe, a compact power hitter from Crofton Country Club, shot a solid 71 and held off a back-nine challenge by Wheeler Stewart to win his second Maryland Open yesterday at Crofton.

Graefe won in 1976 at Woodmont as an amateur. "Winning this the first time was the biggest thrill of my golfing career. Winning it the second time in front of all of my friends is even better," said the 26-year-old son of golf pros Ed and Tic Graefe.

Graefe shot a competitive course-record 68 on the 7,100-yard layout Tuesday, and his one-under-par score yesterday enabled him to finish two shots ahead of Stewart of Congressional. Stewart shot the day's low round, 69. Graefe's 54-hole total of 214 won $1,750. Stewart took home $1,190.

Graefe began the day tied with Rick Hughes and was two shots ahead of Woody FitzHugh. All three played in the same group yesterday. After shooting even-par 36 on the front nine, Graefe had a four-shot lead on his playing partners, but he had a new problem. Stewart, the winner in 1979 who was playing in the group ahead, shot 34 on the opening nine and had closed to within two strokes.

Stewart birdied the par-4 13th hole, then rolled in a 30-foot birdie putt at 15 to pull even. Graefe made a birdie at the 16th hole to regain the lead. At the par-5 16th, Graefe yanked his second shot left into rough, 60 yards short of the green. He had a downhill lie and had to hit over a sand trap guarding the front of the green. He chose a sand wedge, hit the ball eight feet from the cup and sank the putt for birdie.

Stewart, meanwhile, had hit his tee shot one foot off the green at the par-3 17th hole. When he heard the gallery cheer Graefe's birdie putt at 16, Stewart said he knew he was a stroke behind. He almost holed his chip shot, but the ball rolled seven feet past the cup. He missed the putt, took bogey and Graefe suddenly had a two-stroke lead.

Graefe parred his final two holes for victory. FitzHugh finished third at 74-219, followed by Hughes, 77-220, and Gary Marlowe of Woodmont, who was low amateur, 73-222.