The world number seven fired a seven-under par round to join Inbee Park atop the leaderboard at the halfway stage of the event in Taoyuan County in Northern Taiwan.
Petterson, who won a play-off at the Hana Bank Championship in Korea on Sunday, had a bogey free-round while overnight leader Park carded a 69 to reach 10-under-par.
World number one and defending champion Yani Tseng also shot 69. She is eight under and in joint third place with Scotland's Catriona Matthew.
Matthew, who lost on the third hole of that play-off to Petterson, carded a 66 after making birdie at the first three holes.
American Alison Walshe (67) is alone in fifth at six-under-par at the Sunrise Golf and Country Club.