Abstract: Hydraulic Mechanical Continuously Variable Transmission（HMCVT） can withstand large torque, the transmission range is relatively wide, suitable for high-power tractors. The wet clutch is a clutch plate immersed in the transmission fluid, which is a key component in the high-speed CVT and can achieve smooth power transmission. Therefore, it is important to study the dynamic characteristics of hydraulic continuously variable transmission（HMCVT） and conduct wet clutch test to improve the working performance of high horsepower tractor in the field and extend the service life of the machine. In this study, virtual models of gearbox, pump-controlled hydraulic motor system and shift hydraulic system were established based on AMESim, and the operating conditions of the high horsepower tractor under working conditions and the internal and external meshing forces of the planetary row were simulated and studied, and finally, the wet clutch engagement process of HMCVT was tested on a high-power tractor. The simulation results show that with the increase of throttle opening, the value of internal and external meshing force becomes larger. At the moment of gear change, the planetary gear meshing force has a great impact. The simulation results show that the inner and outer meshing force values become larger as the throttle opening increases. At the moment of gear change, the meshing force of planetary gear has a great influence; the clutch test shows that the oiling curve obtained from the test bench test is similar to the change trend of the theoretical curve, and the fit is high, which indicates that the simulation results are more reliable.