The heat transfer in solid-fluid coupling system relates to not only the heat transfer process in solid and fluid bodies but also the physical quantity exchange through the boundary. Because some boundary conditions, such as heat flux and coefficient of heat transfer, are uncertain, neither solid body nor fluid body can be separated from the coupling system when the thermal coupling analysis is carried out. A coupling analysis method based on numerical simulation codes ABAQUS and FLUENT was put forward to solve the boundary problem. The two simulation codes were controlled by the interface software which was developed to exchange the boundary conditions between solid and fluid models at each iteration step. A copper finned radiator model and its corresponding air model were built by ABAQUS and FLUENT respectively, and the heat elimination process of the radiator under forced convection conditions was investigated. The heat elimination characteristic of an aluminium radiator was also researched. By comparing with the copper radiator, it can be found that the larger the coefficient of heat conductivity is, the higher the heat elimination efficiency is.