Abstract: The attitude optical sensor is the basis of the attitude control of the spacecraft on orbit, and the installation accuracy of the sensor determines the attitude control accuracy of the spacecraft. To study the influence of the internal pressure on the attitude optical sensor installation accuracy, based on the internal pressure of the manned spacecraft on orbit, the installation accuracy and the sensor installation and the deformation of the module are analyzed, a method of the sensor installation evaluation is developed, and the experiment of the internal pressure simulation is carried out. The results of the experiment show the accuracy of the analysis. Based on the results of the analysis and the experiment, the assembly accuracy is ensured.