The 18-year-old Jutanugarn had a 13-under total at LPGA International. The final top 20 in the five-round event will earn full tour status.
Japan's Ayako Uehara was second, also after a 69. Toronto's Rebecca Lee-Bentham (67) and Lacey Agnew (74) of the U.S. followed at 5 under.
"Everything's going well, but not my putting," Jutanugarn said. "The pins were tricky today. I didn't really make putts. I had only three birdies and no bogeys. That's good with no bogeys, but I didn't make any putts. ... Just trying to do my best and play my best. If you win or get 20th it's the same thing."
Stephanie Sherlock (71) of Barrie, Ont., is tied for fifth with four other players.
Two-time tour winner Christina Kim of the U.S., tied for third entering the round, had a 75 to drop into a tie for 13th at 2 under. She is playing the qualifying tournament for the first time in her career.
Samantha Richdale (71) of Kelowna, B.C., and Sue Kim (74) of Langley, B.C., are in a group tied for 61st, Izzy Beisiegel (76) of St. Hilaire, Que., is tied for 100th, Hamilton's Ashley Sholer (76) is tied for 104th and Kirby Dreher (73) of Fort St. John, B.C., is tied for 111th.