Lee was worried that he would think more about going to Augusta National than his golf at Nanshan International. That was never a problem. He stretched his lead to as many as six shots on the back nine. Even with a bogey on the last hole, he finished with a 1-under 70 to win by three over Shohei Hasegawa of Japan.
The winner of the Asia-Pacific gets an invitation to the Masters and is exempt until the final qualifying stage for the British Open. Hasegawa also gets into final qualifying for the British Open.
Defending champion Guan Tianlang shot 73 and finished eight shots behind.
Lee tied for second along with Rory McIlroy last week in the Korea Open, and he kept his form all week in tough conditions at Nanshan. He finished at 3-under 281, the only player to break par. Hasegawa birdied two of the last three holes for a 71.
"Playing in the Masters has been my dream since I started playing golf," said Lee, who won the Dongbu Promi Open on the Korean tour last month. "I didn't think I would have an opportunity, so this is a great honor, as is playing in International Final Qualifying for the (British) Open Championship. I have never been so excited."
Lee made bogey on the second hole to briefly fall into a tie for the lead with 16-year-old Dou Zecheng of China. Dou bogeyed the next two holes, however, and Lee began to pull away.
"I have been looking at the leaderboard since the third round and I was a bit nervous," Lee said. "I just tried to keep calm and it seemed to work. I knew I was going to win after the tee shot on the 17th hole. Everything worked well during the last two rounds.
"I can't believe I am going to go to the Masters," he said. "I think I will only realize it tomorrow."
Hasegawa made a 15-foot birdie putt on the final hole to win the silver medal as the runner-up, which got him into the final stage of British Open qualifying.
"My putting let me down over the weekend, and I hope to return next year to get the trophy," Hasegawa said. "But I'm very glad to have a chance to qualify for the (British) Open. I think this is a great chance for my golfing career."
Since the Asia-Pacific Amateur began in 2009, all but one winner has made the cut at the Masters—Hideki Matsuyama twice and Guan last year. Guan was 14 in April, making him the youngest player to make the cut in any major held over 72 holes.
Starting the final round five shots back, Guan failed to make a birdie Sunday.
Oliver Goss, already in the Masters as the runner-up at the U.S. Amateur, was making a move with a 34 on the front nine until taking a triple bogey on the 10th hole and a bogey on the 11th. His 72 left him seven shots behind.