Abstract: The spindle system heat problem is a key problem that must be considered for high precision machine tool. The thermal contact resistance( TCR) affects the heat transfer performance of a machine tool,which affects the machining accuracy. In this paper,a model considerating the bulk resistance and shrink resistance surface of TCR was established by using the fractal theory of the contact surface. Motor heat and bearing friction heat in a vertical machining center motorized spindle system were analyzed. In case of considering TCR and without considering TCR,steady state temperature field and the steady state thermal deformation were analyzed.Resultsdemonstrate the importance of TCR to the problem thermal characteristics of motorized spindle. The temperature will be higher and the deformation will be serious when TCR is considered.