The relation of temperature level function with the outside surface solar absorptivity,outside surface emissivity,inside surface emissivity,angle of sun incidence is fitted respectively. The relation of temperature difference function with the thermal joint conduction and the heat conduction of drawtube is fitted respectively. The curve fitting function formula accords with the theory. The result shows that when the outside surface solar absorptivity and emissivity change from 0.05 to 1,the changes of temperature level in the star sensor system are 149.89 ℃ and 147.44 ℃. The effect of the inside surface emissivity on the temperature level is obviously smaller than that on the outside. When the angle of sun incidence is ±11.97°,the temperature level is the highest. The temperature difference effect of the thermal joint conduction and the heat conduction of the drawtube has a non-sensitivity region. When the thermal conductivity is more than 60 W/(m·K) and 200 W/(m·K) respectively,the thermal conductivity effect on the temperature difference is small.