BEIJING, Oct 14, 2012 (AFP) - Yang scored a two-under-par fourth-round 69 to overnight leader Liang's 73 to leave both at eight under for the tournament. 
They then matched each other shot-for-shot as they played the 18th five times to try to settle the OneAsia $1 million event.
Neither player has won on any tour since each claiming two OneAsia titles in 2010. For a time it seemed that Australian Aaron Townsend (72) might pip them both in the final round.
But Townsend stuttered down the finish, and missed the playoff by one stroke after two bogeys in the last five holes.
"I'm very happy," Liang said after sinking his putt in fading light at the Nanshan International Golf Club's Danling course.
"I have never been involved in something like this. Thanks to Y.E. for making it so exciting," he said, according to a statement from the organisers.
Yang, who won the 2009 PGA Championship to become the first Major winner from Asia, said he was disappointed that his final-round charge did not succeed, but added that Liang was a worthy winner.
Louis Oosthuizen, the 2010 Open Champion, was three shots off the pace after a final-round 67. He ended in joint fourth place with Wang Jeung-Hun of Korea and American Garrett Sapp, who both closed with 69s.
"There were a lot of birdie opportunities but I just didn't make as many as I could have," the South African said. "It is a bit frustrating when I think of the missed opportunities on the first two days."
Liang earned around $180,000 for his fourth victory on OneAsia.
Leading scores:
276 - Liang Wenchong (CHN) 68-67-68-73, Y. E. Yang (KOR) 71-68-68-69
277 - Aaron Townsend (AUS) 69-67-69-72
279 - Louis Oosthuizen (RSA) 71-72-69-67, Wang Jeung-Hun (KOR) 69-71-70-69, Garrett Sapp (USA) 73-70-67-69
280 - Michael Hendry (NZL) 72-73-67-68
281 - Steven Jones (AUS) 68-74-72-67, Rory Hie (INA) 74-69-69-69, Scott Laycock (AUS) 70-71-70-70