Objective To explore the lower limb motor coordination and stability of older adults over 65 years oldduring Tai Chi brush knee and twist step. Methods A total of 30 Tai Chi practitioners randomly completed walkingand brush knee and twist step. The lower limb kinematics datawere collected by Vicon three-dimensional (3D)motion capture system. Results During brush knee and twist step, the joint angle in sagittal plane and continuous relative phase ( CRP) values of hip-knee and knee-ankle joints during brush knee and twist step changed frequently. The mean absolute relative phase (MARP) for hip-knee and knee-ankle joint and the mean deviation phase ( DP) for hip-knee joint were significantly lower than those during walking. Conclusions Compared with walking, the hip-knee and knee-ankle joints present a more coordinated and stable segment motion pattern during Tai Chi brush knee and twist step. Tai Chi exercise may provide a specific coordination training method for older adults, enhance posture stability and prevent falls