Infrared optical systems, facing with complex external environment, are widely used in military, aerospace, civil and other fields. The traditional method for evaluating system performance just by Optical Analysis Software should be improved, and thermal/structural/optical (TSO) integrated analysis is an effective method for synthesizing effects of multiple physical fields, which include optics, mechanics and thermology. The data conversion program between disciplines was compiled after researching Zernike polynomial fitting algorithm. The interface problem of data transmission in optical mechanical and thermal program was solved, and the thermal insensitivity optical system design was carried out using the TSO integrated analysis, as an example. The optical transfer function of infrared system under the high and low temperature environment was obtained by TSO integrated analysis, which provides a theoretical basis for the improvement of system design and performance.