Abstract: In order to reveal the movement mechanism of kangaroo-hopping robot's flexible foot during touchdown phase and its influence on hopping capability,a foot-ground contact analysis model based on hinged-free beam is developed.La-grange equation and the assumed mode method are used to construct dynamic equations of the flexible sole during touchdown phase.Combined with examples,Matlab is used respectively to calculate and simulate the flexible foot's movement gait, change of elasticity potential energy and displacement change of the ankle,and the corresponding change law is given.A contrast experiment platform for flexible and rigid feet of the hopping robot is established,and impact acceleration curves of rigid and flexible feet when landing are measured.Curves of rigid foot are compared with those of flexible foot,and it is verified that it is feasible to use uniform flexible beam as robot's flexible foot to simulate kangaroo's flexible foot,which supplies a powerful evidence for kangaroo-hopping robot design.