Thermal simulation and analysis play a significant role in development of new generation of DC/DC package design and system integration. This paper presents an innovative model for thermal simulation and analysis with the application of active area loading. In traditional model, resistor, inductor, transformer and similar components are usually simplified into a homogeneous body with the same size of package outline. In the current model, the detailed geometry and material are embodied, including the heating area referenced as active area loading. And according to the manufacturing process used for the component, the height of active area is computed by equivalent method.For comparisons, the innovative model and traditional model were developed for the same DC/DC power module with the application of Pro/E software. And the thermal simulation and analysis were processed in the platform of ANSYS Workbench. Under the same boundary conditions and heat convection coefficient, the thermal distributions of DC/DC module were predicted in two models, and verified by infrared thermal images, which shows that the current model is more accurate.