Abstract: A one-legged mechanism model for hopping kangaroo robot with compliant foot is designed based on studying the structure and hopping characteristics of kangaroo,and the kinematic and dynamic equations of relevant mechanisms during the stance phase are established.According to the examples,the following simulation curves with time during the stance phase are obtained by calculation with Matlab 6.5: angle of each joint,contact length between the compliant foot and ground,the ground supporting force,and joint torques.Computer simulation and analysis results show that the take-off time takes 2/3 of the whole stance time;the vertical ground reaction force reaches max when the contact length between the compliant foot and ground reaches max;the input torque of the ankle joint is bigger than that of the hip joint.This work lays a foundation for mechanism design and accurate control of hopping kangaroo robots.