The Englishman completed the best fight back of this year's world championship so far and set up a showdown against another Chinese Ding Junhui.
"I played some good stuff today. My potting was good and my safety was good," said Trump. "The big turning point came at 7-3. He had some chances and didn't take them, and I took a lot of heart from that because I've seen him twitch in tournaments before.
"I think he looked very edgy from the start today and I got it in my head that I could get back into it and put him under pressure. There is a difference between getting back into the game and finishing it off, and I'm very happy about being able to finish off the job."
Liang, who fought back from 5-1 down to defeat Trump 6-4 in the third round of UK Championship last year, said: "In the first session I was confident but today I missed so many balls. I had a good chance to go 8-3 up but I missed and it' s very easy to lose concentration.