Aiming at the problem of large impact force when the robot falls to the ground in jumping motion, in this paper facing to the vertical jumping movement, taking hydraulic quadruped robot single leg as research object, the single leg motion kinematics model of the hydraulic quadruped robot is established, and the trajectory planning when the single leg of the robot is in takeoff phase, flight phase and falling phase is carried out. According to the joint parameters, the driving function is obtained through inverse kinematics solution, and the simulation software ADAMS is used to simulate the vertical hopping gait. The experiment platform for single leg was set up and experiment verification was carried out. According to the obtained dynamic characteristics, the accuracy and rationality of gait planning are analyzed, which provides the design and control basis for the following study of the dynamic gait of hydraulic quadruped robot.