The purpose of this paper is to find a proper cooling system of bearing unit in the submersible motor pump to extend a life time. To do this, heat transfer analysis of the submersible motor pump were performed using commercial CFD code ANSYS. In order to obtain the resonable heat transfer simulation results, we first set up mathematical model of heat source in the bearing system, and carried out heat transfer analysis with the model. As a results, new type bearing cap which had several ribs for cooling the bearing was proposed. Finally, through the comparison between experimental results of old and new model pump, we proofed that maximum bearing temperature of new model was about 10% lower than that of old model.