Abstract: The model of hydraulic mechanical variable transmission(HMT) is very difficult to solve the real-time because of complication including nonlinear changeover process, so it is impossible to realize controller hardware-in -loop(HIL) in real time. Controller HIL based on sync signal was proposed, the clock of the controller HIL based on sync signal and the sync signal period were defined and subsequently time sequence error of controller HIL based on sync signal was analyzed. The controller HIL simulation system of HMT was established based on controller HIL using sync signal. The simulation results of the two stages of HMT demonstrated that the control effect of the controller hardware-in-loop was approximately the same as controller model using same control strategy when the engine throttle changed.