The Chinese teenager will face 2010 world champion Neil Robertson on Thursday for a place in the semi-finals after holding his nerve in the final frame against Dale, a winner of the Shanghai Masters in 2007.
Dale established leads of 3-1, 4-3 and 5-4, but was left helpless as Lu - who was due to face Ronnie O'Sullivan in the first round before the world champion withdrew due to illness - collected the final two frames to illustrate why he is the youngest player to become world under-21 champion.
Lu contributed 99 and 86 to restore parity at 3-3 with Dale failing to score heavily enough to douse his young opponent's adventure.
Lu is already the youngest player to win a televised match having outlasted Marco Fu 5-4 in the wildcard round of the Shanghai Masters in September. He defeated Michael White 6-5 in the wildcard round of this tournament.
Robertson always had too much scoring muscle for Dale's fellow Welshman Matthew Stevens, a former UK and Masters champion who paid a heavy price for failing to pile on the points among the balls, an aspect of the game where Robertson is rarely found wanting.
"Through to the quarters with a win over Matthew Stevens," said Robertson on Twitter. "Played quite well, hopefully keep it going."
Stevens won a scrappy opening frame before Melbourne man Robertson exuded his typical scoring instincts in a part of China that is synonymous with the giant panda rather than gigantic breaks.
Robertson produced 100, 63, 75 and 85 amid a measured tactical approach. Stevens' highest knock of 38 in collecting frame six was not really telling enough at such an exacting level of the sport.
Elsewhere, Peter Ebdon shrugged off his grinder tag as he devoured Stephen Maguire 6-1 to secure a meeting with Ricky Walden in the last eight.
Ebdon enjoyed knocks of 89, 61, 52 with Maguire's 61 in snaring frame three a minor consolation on a largely forgettable day for the Scotsman.
Maguire has never disguised his dislike of facing Ebdon. His travails continued after losing 10-9 to the 2002 world champion in the final of the China Open in April, a contest that lasted over seven hours.
It was a lot more routine today with Ebdon getting the job done in two hours and 33 minutes.
Ebdon continues his quest for a 10th ranking title and a first prize of £125,000 for carrying off this event.
Walden, meanwhile, beat world number one Mark Selby 6-3 in a marathon that ended after 1:30am local time.
Marco Fu outlasted Mark Davis 6-4 in a lengthy match that had to be completed after the evening session with Fu 5-4 ahead from the afternoon.
Davis needed to oust Fu to dock in the game's top 16 for the first time in his career ahead of the UK Championship in December and the Masters in January, but came up short.
Fu will face Shaun Murphy, who staved off a recovery by Ding Junhui to win 6-4. Murphy won four of the first five frames to lead 4-1 aided by a 59, 45, 103 and 78.
Ding ran in a 66 in the seventh frame on his way to levelling at 4-4, but a timely 108 displayed Murphy's resolve before he pinched a scrappy 10th frame to complete a win his play probably merited.
World number two Judd Trump secured a meeting with Mark Allen in the last eight after a 6-0 drubbing of India's Aditya Mehta, who was appearing in the last 16 of a ranking event for the first time.
Trump made breaks of 49, 98, 48, 44, 63, 49 and 65 to progress. Allen pieced together 41, 42, 59, 44, 51 and 80 in ousting Cao Yupeng 6-2. It was a measure of revenge coming against a figure who had upset him in the first round of last year's World Championship.
International Championship quarter-finals Thursday (best of 11 frames) 6.30am (GMT) Peter Ebdon v RIcky Walden Judd Trump v Mark Allen 11.30am (GMT) Neil Robertson v Lu Haotian Shaun Murphy v Marco Fu
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