This research applied CAFIAS system observation method to analyze the interactive behavior between physical education teacher and students in swimming teaching, and concluded as fallows: (1) Physical education teacher is focused to direct influence in swimming teaching, in which the teacher behavior made up 68.68% and student behavior made up 25.50%, the percentage is close to 2.70. (2) Teacher behavior is based on oral expression and centered on giving information 30.60%, which shows that the teacher is focused on giving information to student. (3) Student behavior is based on non-oral expression, and the highest behavior is the understanding of teacher 14.27%, which shows that students practice hard for the swimming skill taught by teacher.