The purpose of this study is to examine the lesson strategies of middle schools’ physical education(PE) teachers on the coeducational class. Five PE teachers’(2 males and 3 females) classes in 3 middle schools are observed. In-depth interviews with that PE teachers are used to collect relevant data. The collected data are analyzed by the case analysis and inductive categorical analysis. The results of the study are followed. First, lesson strategy of PE teachers on the instructional objectives is ‘downward equalization’ falling down the qualitative level of the instructional aim. Second, lesson strategy on the instructional contents is ‘superficiality’ not performing the instructional contents faithfully. Third, lesson strategy on the teaching methods is ‘together and separately’. It includes ‘teaching method of separation’ that schoolboys and schoolgirls act separately in same class, and ‘teaching method of two times instruction’ that the teacher teaches schoolboys/schoolgirls after teaching schoolboys/schoolgirls. Finally, assessment strategy on the co-educational class is ‘another separation once more’ that the teacher assesses schoolboys and schoolgirls separately.