Abstract: Teenagers' learning degree of freedom in physical education is one of the issues to be solved in teaching, which has not been fully explained in theory for a long time. Based on previous studies, the teenagers' learning degree of freedom is explored in physical education from a student-oriented perspective. The results show that autonomy, decision-making and self-discipline are three important dimensions interrelated as a whole, among which, autonomy is the motive power, decision-making is the medium while self-discipline is the highest level. Based on this, the endogenous evolution mechanism from autonomy to self-discipline has been established, with the essence of students' inner moral awakening, making rules on their own and following them. Combined with the teaching practice, several practical strategies are put forward for teenagers' learning degree of freedom in physical education from the aspects of students, teachers, teacher-student relationships, teaching modes and teaching methods. They are to expand optional courses of the whole learning periods, improve the style of teaching management, avoid indoctrination and let students make decisions independently, give priority to comprehend teaching modes, and cater for their abilities.