There was also a 5-3 win for former world champion Mark Williams, who dropped the opening two frames of his encounter with Mark Allen before winning five of the next six frames to ease himself into the quarter-finals in China.
World number 36 Milkins made a vibrant start to his match as he pocketed the first frame with a run of 56 only for Trump to come up trumps with knocks of 137, 85 and 49 in moving 3-1 clear at the mid-session interval.
Gloucester's Milkins did not take the news well as he came out revitalised to secure his progress with a 55 seeing him recover from 52-9 behind to close to 3-2 in the match, a key moment in changing momentum.
A 48 and 35 saw him move 4-3 clear before a closing break of 61 helped him over the line after Trump broke down on 36 trying to force the deciding frame. Milkins will meet Ricky Walden after he overcame Joe Perry 5-4 in the last eight on Friday.
Williams was never at his best against Allen, but did not have to be as his matchplay skills helped him account for the world number 12.
Allen pocketed the opening two frames with Williams restoring parity at 2-2 despite his break of 39 in the fourth frame being the highest of the match.
Williams eked out the fifth frame on the pink and black with Allen doing likewise in the sixth frame before Williams clambered over the line by picking up the next two frames as Allen could only come up with a measly 10 points in departing the tournament.
World number three Williams and world number one Mark Selby are the only players inside the game's top 12 remaining in the event after a series of surprising results in the opening ranking tournament of the new season. Williams will face Marcus Campbell in the last eight after the Scotsman overcame Fergal O'Brien 5-2.
Australian Open holder Stuart Bingham made breaks of 143 - the highest of the week so far - and a 124 on his way to edging past 1997 world champion Ken Doherty 5-4. It was his second win over a former champion in the final frame after a 5-4 success against Peter Ebdon in the previous round.
Bingham will next meet Selby, who ousted a faltering Jamie Cope 5-0 aided by top breaks of 52 and 80.
2006 world champion Graeme Dott ended the impressive run of qualifier Rod Lawler - who had to negotiate seven rounds to reach the last 16 - by claiming the final two frames with runs of 55 and 85 to complete a 5-4 win while there was a 5-3 win for Mark Davis over Jamie Burnett.
Wuxi Classic quarter-finals (Best of nine frames)
Friday schedule in China
Mark Selby v Stuart Bingham
Mark Davis v Graeme Dott
Mark Williams v Marcus Campbell
Ricky Walden v Robert Milkins