The defending world champion raced into a 3-0 lead courtesy of back-to-back centuries but was pegged back to 4-4 after the interval in Yushan, China.
However, he finally came through in the ninth frame to book a match with Liang Wenbo.
Trump claims second title of season with World Open victory over Un-Nooh
'Not naughty snooker… it’s scary snooker!' - Trump sinks 144 break
Earlier, John Higgins scraped through with a 5-4 win over Lu Ning – despite inviting his opponent back into the match after a horror miss in the sixth frame.
Higgins needed to cut in a simple black for a 4-2 lead but contrived to miss the final ball completely.
‘I’m quite shocked by that’ – Higgins with horror miss
He was then pushed the distance by a grateful Lu, who was ultimately unable to claim the scalp of the four-time world champion. Higgins next faces Mark Davis.
Thailand’s Thepchaiya Un-Nooh became the 69th player to reach 100 career centuries in a 5-1 dismissal of amateur Zhang Yang.
Breaks of 104, 85, 102 and 65 were more than enough to book a second-round meeting with Craig Steadman.
Higgins beats Bingham to set up Trump clash in World Open semi-finals
Trump sneaks past Perry after gripping 38-minute decider