In order to ensure that the leg-foot mechanism of the buffering/walking lander does not produce larger impact and vibration in the process of movement， a trajectory planning in joint space of the leg-foot mechanism is carried out. The optimal trajectory is obtained by taking time-jerk as the optimization objective. Firstly， the leg-foot mechanism of hexapod lander with the buffering and driving functions is introduced. Its kinematics is deduced and its buffering performance is analyzed. Secondly， the mapping nodes of the key points of the foot-end trajectory in the joint space are obtained with inverse kinematics， and the nodes are fitted with cubic splines. Thirdly， the optimal time-jerk trajectory planning model is established with the node time interval as a variable. Finally， the model is solved by using multi-population genetic algorithms. The results show that the leg-foot mechanism has stable and continuous movement performance， and the planned optimal time-jerk trajectory is reasonable and effective， and there is no larger impact and vibration during the movement of leg-foot mechanism.