The big-hitting 27-year-old from Guangzhou carded four birdies over the final six holes to pull clear of the field.
The big-hitting 27-year-old from Guangzhou carded four birdies over the final six holes to pull clear of the field after a low-scoring first day at the Tiburon Golf Club in Naples.
Feng, chasing her third win of 2016 after victories at the Toto Japan Classic and Sime Darby LPGA Malaysia, made two birdies and seven pars to reach the turn at two under.
But the Chinese star cut loose over the back nine, making back-to-back birdies on the 13th and 14th before another pair on the 16th and 17th. Her 12th par of the day on 18 completed a solid opening round for the world number four.
Feng is one shot clear of South Korea's Ryu So-Yeon and England's Charley Hull, who are tied for second after carding five-under-par 67s.
Hull looked to be mounting a charge after reeling off four consecutive birdies on the sixth, seventh, eighth and ninth to reach the turn at four under.
But the 20-year-old Englishwoman's momentum stalled over the back nine and she added just one more birdie to settle for a five-under-par first round.
Behind Ryu and Hull were a tightly bunched group of eight players tied for fourth on four under. They include a trio of Koreans, Jang Ha-Na, Kim Sei-Young and Chun In-Gee.
Four players -- Japan's Haru Nomura, Paula Retu of South Africa, Canada's Alena Sharp and Brittany Lincicome -- were a shot back on 69, three off the lead.
New Zealand's world number one Lydia Ko, meanwhile, was four off the lead after recovering from a disastrous start to post a two-under-par 70.
Ko is aiming to overhaul Thailand's Ariya Jutanugarn to claim the $1 million on offer for the winner of the CME Globe title, the LPGA Tour's points race, but dropped two early shots when she double-bogeyed the par-four second.
However, the 19-year-old regained her composure after that setback, clawing back a shot on the par-three fifth with a birdie before three more birdies over the back nine got her to within striking distance of the lead.
Ko's main rival Ariya, meanwhile, suffered a wayward round, finishing with a level par 72 after three birdies and three bogeys.
Ariya remains the favorite to win the points race, however, leading Ko by 500 entering the season-ending tournament.