The brake operation load and shift operation load simulation models were built based on the multiple load coupling function of the transmission oil supply system.The whole transmission oil supply system model was built with these models. The simulation was based on the extreme work condition at the max and minimum rotational speed and the load functioning simultaneous. The main load flowrate and pressure were consistent with the test experience of the transmission oil supply system. So the simulation model is verified. This model provide reference for optimizing the transmission oil supply system.