In order to realize the control for multi- range hydro- mechanical continuously variable transmission（ HMCVT） in tractor,the fuzzy adaptive PID control for multi- range HMCVT in tractor is studied.The transmission system dynamics model of tractor and fuzzy adaptive PID control model are established based on Matlab / Simulink platform. According to the actual deviation of the actual vehicle speed and the target vehicle,the fuzzy control method is adopted to automatically adjust the PID control parameters,so as to achieve the purpose of control. The fuzzy adaptive PID control simulation on the tractor dynamics model and comparison with the PID control simulation. The results show that the stronger adaptive ability and robustness of fuzzy adaptive PID control of tractor.