To solve the problem of heat reflow in the fan rotation center of the forced convection cooling system in the engine compartment, this study established a calculation model of the external flow field of the engine compartment’s cooling module. It then used the CFD numerical simulation method to calculate and analyze the heat flow characteristics of the existing radiator and compared these with the experimental results. Accordingly, the region where the heat reflux occurred and the reason for the heat reflow were found. The existing heat dissipation scheme was recalculated by using the secondary heat dissipation model, and an optimized and improved scheme was proposed to introduce a deflector cone structure to eliminate heat reflow. The research results showed that the secondary heat dissipation model could more accurately describe the heat reflow problem of the engine compartment, the heat flow organization of the improved structure was more reasonable, and the temperature distribution was more uniform. Moreover, the theoretical heat dissipation effect of the improved structure was more than 10% higher than that of the existing structure.