Effect of sliding geometry on the surface temperature of polyoxymethylene(POM) for wear testing was studied numerically. Exact estimation of the temperature on sliding surface of plastic is important for the prediction of wear amount. However, direct measurement of the surface temperature is very difficult during sliding. Therefore, numerical simulation must be powerful tool for it. From this point of view, the authors previously developed the numerical simulation code for predicting surface temperature of hollow circular cylinder made of POM. It was found that the numerical results well explained the experimental results with ON-OFF operation. Moreover, it was found that forced convection due to rotation was significant for the temperature. In the previous study, both of sliding surfaces had same areas and no free surface. In this study, effect of sliding geometry with various contact areas on the surface temperature was numerically investigated. Numerical model consists of two hollow cylindrical POMs and metallic shaft inserted the continuous part. The governing equation of model is three-dimensional heat conduction equation, and frictional heat and heat transfer by forced convection are associated with the boundary condition. These equations were discretized by the finite volume method and solved by TDMA algorithm. Numerical simulation results were compared with the experimental results, and a good agreement between both results was found.