Feng notched her second victory of the season and third of her career, finishing at 15-under-par 273 -- a new a tournament record.
Overnight co-leader Gerina Piller carded a 3-under 69, claiming sole possession of second at 14-under.
Another third-round leader, Pornanong Phatlum, registered a 2-under 70, ending alone in third at minus-13, while Sandra Gal (69) took fourth at 12-under 276.
Inbee Park (68) claimed fifth one stroke further back.
Natalie Gulbis, tied for the lead with Piller and Phatlum after 54 holes, blew up to a 10-over 82 Sunday, falling into 29th-place tie at minus-1.