Objective To determine the effect of Tai Chi practice on balance control ability of the individuals with functional ankle instability (FAI) in single-leg stance, and further observe the augmented effect from attention focus on ankle. Methods A total 46 individuals with FAI were randomly divided into ankle focus group, free focus group and control group. The ankle focus group and FFG performed Tai Chi practice for 10 weeks; the ankle focus group focused their attention on the ankle joint, while the free focus group didn’t require attention focus; the control group maintained the origin lifestyle and didn’t engage in special physical activities. The three-dimensional force plate and Y balance test (YBT) were used to evaluate the static (with eyes open and closed) and dynamic (instant and continuous) balance ability of individuals with FAI. Results For ankle focus group and free focus group, the anterior-posterior (AP) and medial-lateral (ML) sway distances of center of pressure (COP) in single-leg stance (SLS) with eyes open and closed were significantly reduced, and the reach distance in YBT in three directions were increased. For the ankle focus group, the medial lateral stability index and the dynamic postural stability index were significantly reduced during single-leg drop landing. The ankle focus group and free focus group got significantly smaller ML COP sway distance than control group in SLS with eyes open; the ankle focus group got significantly smaller ML COP sway distance than free focus group and control group in SLS with eyes closed; and reach distance of ankle focus group in posterior-medial & posterior-lateral direction in YBT was longer than of free focus group and control group. Conclusions Tai Chi practice can comprehensively improve static and dynamic balance control ability of the individuals with FAI in SLS, and ankle attention-focused Tai Chi practice is more effective, especially for the enhancement of their medial-lateral control ability in closed-eye static and continuous dynamic SLS.