Abstract: In order to improve the carrying capacity and operation stability of the foot robot, a quadruped robot based on 3UPR parallel mechanism was proposed and its motion performance was analyzed. Analyzing the degree of freedom of the robot structure based on the spiral theory, and performing kinematics analysis for the robot leg mechanism based on a position reversal model, the drive feed amount and drive speed were obtained. Comparing the data of ADAMS simulation with theoretical calculation results, the correctness of the model was verified. The singularity was analyzed based on the velocity Jacobian matrix, and the diagonal gait planning on the robot was carried out according to the trajectory of the single leg. The results show that, the mechanism possesses three degrees of freedom, including the rotation in the <i<X</i< and <i<Z</i< directions and the movement in the <i<Y</i< direction. There is no any singular positions in the mechanism movement, showing better motion performance. The gait simulation results show that the robot can achieve smooth motion on the flat ground with a forward speed of 135 mm/s.