Abstract: We introduced the structure characteristics of the stitched optical window modules, analyzed the main assembly factors that affect the performance of the stitched optical window, carried out the research on the assembly key technologies from two aspects, assembly height homogenization and micro-stress setting. Through calculation, analysis and the measures of parameter quantification, the technical problems of alignment were solved.The height homogenization is less than 0.2 mm and the stress loading is less than 50 nm/cm, which achieves high precision and micro stress-loading effect after assembly. It can meet the operation requirements of the optical resolution and high speed flight.