Abstract: As the interface with the outside space environment simulation system, optical window is an indispensable important component parts. Space environment simulation system consists of two types of optical window. Based on both the windows, in this paper, components structure scheme design was carried out respectively. The strength theory formula was used to check the intensity of the window components; The finite element analysis software was used to calculate the effect of pressure on the optical glass surface deformation, and to analyze the impact of optical glass surface deformation results of the optical properties of the optical window assembly. The results show that aperture 150 mm, the work stress of optical window assembly is 0.82 MPa; Aperture 350 mm, the work stress is 3.28 MPa, meet the strength requirements. Zemax software was used to calculate the wavefront error(PV)of aperture 150 mm optical window assembly is /8; within 170 mm-190 mm band area, the optical path difference of aperture 350mm optical window assembly is 0.8 nm; Both of them can satisfy the requirements of optical performance. Therefore, this design meets not only the strength and reliability requirements, but also the optical performance requirements, So the design of entire window assembly is safe and reliable.