Abstract: This paper presents a new real time control method for biped dynamic walking. By introducing some new concepts of posture stability and gait stability, the control system of biped is separated into two interconnected sub systems of posture control and gait control. Based on the analysis of the posture stability, problems of the trajectory servo control of each joint and the dynamic pendulum of the whole mechanism are studied in detail. The structure and the design method of posture controller are given.