Abstract: In order to expound the temperature characteristics of homogeneous material reflective system in principle, and provide the basis for the design of optical system, the temperature characteristics of single mirror, coaxial multi-mirror reflective system and off-axis reflective system were introduced successively, which were based on the thermal deformation characteristics and its calculation method, and the optical system focus was taken as the research object. Meanwhile, the corresponding thermal aberration model of reflective system was established. The simulation results show that the change of focal length with temperature in the off-axis three-mirror reflective system is completely consistent with the thermal deformation amount of corresponding lens barrel, and it has good imaging quality in the range of large temperature difference. The thermal defocus caused by the temperature change can be compensated by the lens barrel, which verifies the correctness of the theoretical model and draw a conclusion that there is no thermal aberration in the homogeneous material reflective system in the condition of uniform temperature field. Therefore, the optical system, especially the infrared system with obvious thermal aberration effect has good temperature adaptability when the homogeneous material reflective system is adopted.