Hubert Green, informed of a threat against his life, just before he teed off on the 14th hole, dropped a three-foot bogey putt on the 18th hole to withstand another threat, that by former champion Lou Graham, to win the 77th U.S. Open golf championship today at Southern Hills Country Club.

Green who had held a four-stroke lead in the final round, finished with an aven-par 70 for a 72-hole total of 278, a shot better than Graham, a former Ft. Meade soldier who served in President Kennedy's honor guard.

Green refused comment on the death threat, referring all questions to police. However, P. J. Boatwright executive director of the U. S. Golf Association, confirmed that a threat had been received by the Oklahoma City office of the FBI and that Green had been told about it prior to teeing off on 14.

Graham who won the Open at Chicago's Medinah course in 1975 in a playoff with John Mahaffoy, was looking for a repeat. And for a moment it appeared that the 18th hole, called "Jaws" by the golfers, was about to devour another victim in Green. If there was any satisfaction for Graham, a soft-talking, 39-year-old native of Nashville, Tenn., it was that he prodicated a month ago that Green would win the Open.

This was the first major title for the 30-year-old Florida State graduate who has been bothered with marital problems and was divorced in January.

"Yeah," said Graham, "I picked Hubie after the Jack Nicklaus Memorial tournament in Ohio. I played with him the last two rounds and I never saw a man play better. I know he was going to do something big."

Green was sixth in last year's Open and has been one of those golfers who makes a lot of money but doesn't attract much attention. He had not won a tournament this year but still was 17th on the money list with $73,752 going into the Open. His $45,000 check today gave him a career total of $874,192. But the title, his 12th on the P G A tour, gave him more satisfaction, he said, than the money.

Green said, "It was nice to win the big one. I really haven't had time to think about how I feel. I'll think tommorow. I've been running to and from a major title ever since I started to golf. It's just nice to win - but it's all in a day's work.

"They talk about choking.I think I choked on the 18th. We all choke. I kept telling myself on the 18th tee: 'Now all you have to do is get a bogey. Don't knock the ball in the left bunker. 'So I hit my drive in the rough and then I hit my four-iron, still telling myself not to knock it in the left bunker. So I did.

"Then I told myself in the bunker. Don't junk the shot.' But I did. I left myself a long putt. I hit a good first putt but it was about 3 1/2 feet short. I was thinking to myself that this was another get-springer.

"This is the kind of course I grew up on. I felt at home here. It's a great course, a tough course, with great greens. I tried to play my game and let the others catch me. I knew I wasn't going back - they had to come and catch me."

As do most U. S. Open courses, the Southern Hills layout proved too tough for the pretenders to the Open crown as they fell back along the way. A disappointed Tom Welskopf, always up front but never the star of the Open, was third with a 281, followed by Tom Purtzer, a stroke behind. At 283 were Jay Haas and little-known Gary Jacobson, 24, an itinerant pro who failed three times to get his playing card on the pro tour.

Tom Watson, the Masters champion, saw his dream of a grand slam go down the drain, but he did come up with a final 67 to finish at 284 along with Lynn Lott and Terry Diehl.

Jack Nicklaus never could make a move and had only one birdie the final round. He finished at 285 with Gary Player and Al Geiberger, also highly regarded before the tournament. Nicklaus never did master the 18th, bogeying it today for the fourth straight time.

Graham had stayed in contention, but little noticed, with rounds of 72, 71, 68. He shot 68 today to give him 136 for the last 36 holes, trying a record held by three others.

"I never hit a shot on the first two holes," he said. "I bogeyed both of them. But then I got going after a 37 (two over par) on the front side. I felt I had a chance to win after I birdied the 14th, 15th and 16th."

Graham almost tied green on the 17th. He put missed the birdie putt.

"It was the best shot I ever hit in my life," he said. "If I had one shot to play over again, it would be on No. 5 where I hit a dog with a six-rion. I got a par but that should have been a birdie hole with a good shot."

After the first round, Green was tied but never out of the lead. He had rounds of 69-67, 72 and 70. His margin today varied from four shots to two to one.

He and Andy Bean, a former amateur star from the University of Florida, were paired, but the duel many expect never materialized.Bean was only a stroke back starting out and expressed confidence that he would be somewhere "in the reckoning." But the good-natured, 24-year-old finished with a 79 for 288.

Bean's troubles began when he got careless on a two-foot putt on the first hole and missed for a bogey. From there, it was all downhill.

Green parred the first two holes. He hit a fine chip for his third shot that put him a foot away for a par on the first hole. He was in the rough and under a tree with his drive on the second hole. He came out in front of the green, chipped to within two feet and made good. He sank a 20-footer for a birdie putt on the fourth.

He found trouble on the ninth, where he got his first bogey. He left his second shot short, chipped onto the green but the ball rolled off. He got down in two.

Purtzer was now making his move. He birdied the eighth hole and was two strokes behind Green. But Purtzer left the tournament on the 14th, a 207-yard par three, when he put his tee shot out of bounds and took a double bogey.

Now it was Graham challenging. After his third straight birdie, on the 16th, he was one stroke away. But Green put a six-iron shot two feet from the pin for a birdle-4 on the 16th and his margin increased to two shots.