Abstract: The tractor hydraulic suspension system is a key component of agricultural implements and tractor connection, in the tractor factory is often used to manually hook up the way to detect the load-bearing performance of the hydraulic suspension system, there are long time-consuming, low-efficiency, safety hazards and other defects.Under the premise of not changing the existing cylinder loading detection device, this paper according to the four-bar kinematic mechanism designed for large and medium-sized tractor hydraulic suspension system testing of the hook-up device.Combined with the characteristics of the four-bar structure and the relevant provisions of the tractor hydraulic suspension testing, the motion law of the hook-up device is analyzed, and the structure and working principle of the device are described.In the experimental environment, repeat testing of the developed hydraulic suspension hitch device hitch performance.The test shows that: the average hook-up time of the hook-up device is 68.6 s, a hook-up success rate of 96.7%,much lower than the manual hook-up operation time, and has a good hook-up success rate.The developed hydraulic suspension hooking device structure is simple, and reliable performance, reduces the tractor hydraulic suspension testing intensity, and improves testing efficiency, for domestic and foreign tractor manufacturers to design a tractor hydraulic suspension automated testing system to provide a basis.