The 22-year-old left-hander from Oban sits joint-12th alongside fellow Scot David Drysdale heading into the final round of the opening event on the 2019 schedule at Fanling.
MacIntyre, one of four Scots to graduate to the top tour for the new season from the Challenge Tour, backed up opening efforts of 71 and 67 with a four-under-par 66.
His second successive bogey-free effort on a course that demands accuracy, it left him on six-under-par - five shots ahead of Masters champion Patrick Reed.
MacIntyre, who only turned professional just over a year ago after signing off in the amateur ranks with a Walker Cup appearance, birdied the second, fifth, 11th and 17th.
Drysdale is also on course for a high finish at the start of his 18th successive season on the European Tour after carding a 67 in the third round.
The 43-year-old from Cockburnspath signed for a mixed bag of five birdies, including three in four holes after the turn, and two bogeys..
As Englishman Aaron Rai strengthened his position at the top of the leaderboard - he takes a six-shot lead into the last round - it was a tougher day for the three other new Scottish card holders.
Grant Forrest had to settle for a level-par 70 that left him sitting joint-41st on two-under. The 25-year-old from North Berwick reeled off four birdies in a row as he bounced back from a double-bogey 6 at the ninth before dropping two shots in the last three holes.
Liam Johnston had an up-and-down 72, leaving the 25-year-old Dumfries man in a share of 68th spot on two-over, a shot ahead of David Law after the 28-year-old Aberdonian carded a 73.
Rai, a 23-year-old from Wolverhampton, remained firmly on course for a maiden Europwan Tour victory after following his course-record 61 on Friday with a 68 to sit on 16-under.
His nearest challengers are two fellow Englishman - Ryder Cup star Tommy Fleetwood and Matthew Fitzpatrick - with Sergio Garcia a further shot back.
“It’s going to be to try and kind of stick to the same things,” said Rai, a three-time winner on the Challenge Tour, as he looked ahead to the final day.
“I think when you’ve been in a position before and where you’ve led and where you’ve won, it certainly helps. But it’s a different stage and it’s a different level.”
Elsewhere, Scottish duo Russell Knox and Martin Laird slipped a spot to joint-eighth after the third round of the ISPS Handa World Cup of Golf in Melbourne.
In the second fourball session, the tartan twosome carded a five-under-par 67 for an 11-under-par 205 total at the Metropolitan Golf Club.
That leaves them eight shots behind the leaders, Belgium’s Thomas Pieters and Thomas Detry, heading into the final round, which switches to foursomes.
Pieters and Detry carded an eagle and seven birdies in a 63 as they stormed five shots clear of the field, with Mexico, Italy and Korea leading the chase.