The Japanese star was 11 under on Pumpkin Ridge’s Ghost Creek Course.
Alena Sharp of Hamilton shot 2-over 74 on Saturday and is tied for 44th at 1 over. Adrienne White of Red Deer, Alta., shot 74 and sits tied for 52nd at 2 over. Lisa Meldrum of Montreal shot 75 and made the cut at 3 over after two rounds.
Lorie Kane of Charlottetown, P.E.I., shot 2 over 74, and at 5 over for the tournament missed the cut.
Juli Inkster was tied for second at 8 under with Song-Hee Kim (64) and Na Yeon Choi (67) after an apparent 67, but was disqualified because she used a weighted training aid on her club to stay loose while waiting to make the turn at the 10th hole.
Miyazato has won four tournaments this season and is among five players in a tight battle for the No. 1 spot in the rankings. Cristie Kerr is currently No. 1, followed by Miyazato, Jiyai Shin, Suzann Pettersen and Yani Tseng.