Trump will face Peter Ebdon in their best-of-17 frame semi-final on Friday for a place in Sunday's final after the 2002 world champion Ebdon completed a 6-0 whitewash of a washed-out Ricky Walden.
In the evening matches in Chengdu, Neil Robertson ended the hopes of the spirited 14-year-old Chinese hopeful Lu Haotian with a 6-2 win that was closer than it sounded while Shaun Murphy recovered from trailing 3-1 to complete a 6-4 victory over an inconsistent Marco Fu.
Robertson and Murphy contest the second semi-final on Saturday in a repeat of this year's Masters final which Robertson won 10-6.
Trump managed to hold off Allen 10-8 to win the UK Championship final 11 months ago after the Northern Irishman had recovered from trailing 8-3, and was forced to do likewise today with three centuries and a plethora of high breaks providing some bewitching play.
Allen won the opening frame of the day with an 83, but breaking down on 32 in the second proved fatal as Trump contributed 70 to restore parity at 1-1.
Trump ran in 40 in the third frame - mediocre by the standards of this particular match - to move 2-1 ahead only for Allen to level at 2-2 with a 98 as four frames passed in less than an hour.
The rapid nature of the contest continued after the mid-session interval as knocks of 75 and 107 carried Trump 4-2 clear.
Allen showed his continuing menace when he pounced on a Trump error to make 121 in closing to 4-3 behind only for his opponent to contribute 65 as another frame sped by.
Trump had chances in the next two frames to conclude matters, but rare errors provided his opponent with fresh hope.
Allen made 104 to recover to 5-4 behind after Trump had missed a red from distance. He forced the decider with a timely 40 and a closing 26 after Trump had slipped up by failing to sink another makeable red holding a 41-0 lead.
The tension was palpable in the final frame, but Trump steeled himself with a thoughtful run of 60 providing the platform for his passage to the last four.
Ebdon planted his foot on the throat of Walden early on in their quarter-final and never really released it as a drained Walden paid the price for taking over five hours to defeat Mark Selby 6-3 in a laborious match the previous evening.
He dominated the tactical areas of the contest with 44, 81 and 45 his most piercing contributions. Walden's highest run of 43 summed up his struggles.
Ebdon will return to the top 16 if he can win his 10th ranking tournament. He would also earn a spot at the Masters in January.
Robertson won a couple of frames on black balls as he recovered from trailing 2-1 to claim five straight frames in ousting Lu, who had concluded victories over Michael White and Dominic Dale to reach the last eight.
Lu showed his potential with knocks of 74 and 50, but Robertson always looked the likelier player with a timely 60 and 48 enough to assist his progress.
Murphy somehow found himself 3-1 down against Fu despite knocking in runs of 75, 55 and 55 in the opening four frames.
The 2005 world champion maintained his composure after the mid-session interval as runs of 54, 83, 87, 129 and 51 saw Murphy cut a content figure ahead of the weekend.