In this study, the temperature of solid/fluid inside a continuously variable transmission (CVT) of a 400 cc scooter is investigated numerically utilizing ANSYS FLUENT. The moving reference frame (MRF) technique with conjugate heat transfer between gases and solid rotation/translation are implemented to carry out the simulation. The emphasis of the present study is put on the effects of CVT housing configuration, belt’s thermal conductivity, and the heat dissipated from the crankcase on the thermal-flow-field of CVT.The numerical results show that the temperature of the drive/driven pulleys are concurred with those of experimental results. It is found that the proposed design of partition plate inside the CVT housing can direct the flow into belt and prevent the fluid around driven and drive pulley from mixing, and can further decrease the temperatures of the belt and pulley. The increase of thermal conductivity of belt will increase the average temperature of belt but minimize the temperature difference on it. In addition, the temperature of driven pulley will decrease when belt transition from high ratio to low ratio due to the increase of its rotational speed. The heat dissipation from the crankcase to CVT housing is also explored that the ribs in the housing adjacent to the crankcase served as the fin to enhance the heat transfer from engine to CVT housing. In comparison with the methods proposed by other researchers, this method is found to be the most detailed model.