The 22-year-old compiled eight birdies in a mixed round at the $2.2 million European and Asian Tour event to move two strokes clear of a group of five players including former Ryder Cup player Paul Casey.
Dubuisson, who finished tied fourth at last week's China Open, took 26 putts on Thursday as he chased his first professional title.
"Very pleased with four under today," he said.
"My putting was really good and I think it's the only way to achieve good scoring in these conditions."
Dubuisson's card was marred by a double-bogey six on the fourth and bogeys on the 10th and 16th but he did not let those blemishes upset him.
"On the third hole the wind was from the left and so on the fourth tee I thought the wind was going to be left to right but the wind was turning all the time. It turned right to left and it went into the water," the Frenchman said of his tee shot.
"I was not really upset after that because I didn't hit a bad shot. I did my best to get my concentration back and I made two birdies with good putts on five and six."
Englishman Casey, who has dropped to 45th in the world rankings after missing a lot of golf because of a shoulder problem, was optimistic about his chances of an overdue victory.
"I know if I play the golf I'm capable of then I've got a very good chance to win," he said.
"The way I played today, I need to keep that form going."
World number 11 Adam Scott of Australia, the highest-ranked player in the field, was three behind Dubuisson on 71 after making four birdies in a chilly early start.
"Early on, especially teeing-off at my first couple of holes, it was so cold. I really had no feeling in the fingers and that is tough when the wind is blowing hard," said Scott.
Jung Ji-ho was leading the South Korean challenge on 70 alongside Casey, Scot Richie Ramsay, Englishman Mark Foster and Welshman Jamie Donaldson.
Former US PGA champion Yang Yong-eun (74), struggled in the difficult conditions along with England's Ian Poulter (75) and Asian Tour order of merit leader Jbe Kruger (79) of South Africa.