Environment temperature is the key influence factor for the infrared optical system,so it is necessary to analyze the thermal optical properties of infrared lens.The method based on homogeneous transformation is used to remove the rigid-body displacement.Taking the infrared lens as example,the thermal stress of infrared lens is analyzed by ANSYS software,and the rigid-body displacement of lens is removed.The Zernike polynomial is used to fit the data of mirror surface,and then the fitted results is exported to optical design software ZEMAX for the analysis of optical performance.The results show that the actual service conditions of infrared optical system can be simulated by the method of thermal optical analysis,and the optical performance of this system can be predicted,which has an important guiding significance for the design of opto-mechanical system.