The big-hitting American, who has been one of the headline grabbers in each of the first three editions of the event at Genzon Golf Club, looks to improve on his best finish of a tie for eighth in 2016.
An early bogey on the 12th was the only blemish of his round.
"You know anytime you shoot six under, shoot in the 60s, you're happy with it but every golfer wish they did better. All in all a great day and a good start," said Bubba.
His compatriot Dean Burmester joins him on five under par alongside Frenchman Gregory Bourdy and German Maximilian Kieffer.
Eight-time European Tour champion Thongchai Jaidee also sits one shot off the pace at five under par through 17.
South Africa's Dylan Fritelli (68) is joined by Denmark's Thorbjorn Olesen, Austria's Bernd Wiesberger and Spain's Eduardo De La Riva in a share of third with all set to continue their opening round tomorrow.
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