In order to solve the difficult problem of determining the value of the thermal contact resistance, a calculation method for space camera is brought up from the view of conduction and radiation among the contact surfaces. According to the material, machining, assembly and the actual operating environment, a reasonable range for thermal contact coefficient is obtained. The vertical camera, a sample to show the method, is reasonably meshed into finite element model with some simplification. Its temperature field is computed at low temperature steady-state equilibrium case with I-DEAS / TMG. And then temperature distribution, which is induced by the fluctuations of thermal resistance, is checked. The result of thermal analysis and the data of thermal environment simulation test are consistent very well and the maximum deviation is 0.45 ℃. It is shown that the calculation method of thermal contact resistance is reasonable and it could predict the thermal contact resistance of dry contact precision-machined surfaces in the space environment.