Abstract: For the evaluation and the optimization of the thermal comfort in the cab, a user-defined function with the secondary development of the software Fluent is used to simulate and analyze the thermal comfort in the cab. Based on the international general thermal comfort index, the predicted average thermal sensation index and the predicted dissatisfaction rate, the thermal comfort in the cab is quantitatively analyzed. The influences of the air supply method and the air temperature on the thermal comfort in the cab environment are explored. It is shown that the top air supply can improve the thermal comfort in the cab environment better than the front air supply. Moreover, the thermal comfort degree of the body parts and in the entire cab is evenly distributed. The effects of the air supply temperature on the thermal comfort in the cab are more significant, as compared with that of the air supply method.