Abstract: To solve the unstable problem of the walking quadruped robot destabilized with trot gait,a new method was proposed by changing the initial position of the support foot.Firstly,combined with the principle of zero moment point (ZMP),the optimal initial knee joint angle θ₁ and the hip forward joint angle θ₂ were calculated,and then the optimal initial position was figured out.Simulation results show that the stability of quadruped robot can be different with different initial position.Taking the optimal initial position,the robot body can show the smallest deflection,getting the best stability.It is proved that the stability of the quadruped robot can be effectively improved by adjusting the initial state of the support foot,which is of high practical value in the quadruped robot walking with trot gait.