The function of health care and rehabilitation in Tai Chi has been recognized by the world. Studies on the mechanism of health care in Tai Chi have been conducted by domestic and international experts using the methods of sports biomechanics, most of which focus on human lower extremity. Twenty research literatures (15 articles in English and 5 articles in Chinese) during the year 2007-2015 about biomechanics of the lower extremity in Tai Chi were searched. According to the research purpose and evaluation index, this paper mainly reviewed from 3 aspects: the kinematic & kinetic characteristics of Tai Chi and its influence on the lower extremity, the effect of Tai Chi on muscle activity of the lower extremity, and the impact of Tai Chi movement on interaction between biomechanical parameters of the lower extremity and other system parameters. The prospects and limitations in biomechanical studies on the lower extremity in Tai Chi were also summarized.