The optical axis stability is an important factor affecting the performance of optical system， and the thermal-structural-optical integrated analysis is an effective evaluation method. The thermal-structural-optical integrated analysis process is expounded in this paper， and the rigid body displacement extraction based on homogeneous transformation method is studied. By the use of this technology， the optical axis stability of a HDTV optical system is studied as well. Through the comparison of theoretical analysis and physical test，the correctness of the simulation analysis method is verified. The analysis results show that， compared with the test result， the error of optical axis stability based on the thermal-structural-optical integrated analysis is 12.1%. The thermal-structural-optical integrated analysis can effectively solve the problem of the optical axis stability of highly integrated optical system.