Han had a bogey-free 8-under-par 64 and is ahead by one stroke over five golfers.
That group tied for second includes Keith Horne, who only got 14 holes in Thursday before play was suspended because of darkness. Sergio Garcia is in a group of nine players at 6-under.
After early fog, which caused a one hour delay in the start of play, the players attacked the Luxehills International Country Club in favorable conditions. None of the top six players had a bogey Thursday.
Han, in his first professional season, started his first round on the second nine and was 1-under after eight holes. He birdied No. 18 and opened his second nine with a birdie at the first hole. Han added a birdie at No. 4 before closing with consecutive birdies on Nos. 6-9.
"It's very good weather and I got a bit lucky today," Han said. "I missed a few easy shots, but most of the time I was perfect and hit the fairways and got close to the pins.
"I felt comfortable going into those last four holes, which I birdied. I didn't really feel any pressure and it was a good finish."
Swim Week Miami Beach 2014 [PHOTOS]