In order to solve the crack problem of 800 mm optical glass in a supersonic wind tunnel during the test, the structural form and assembly method of optical glass were optimized. Under the condition of meeting the strength requirements, the thickness of the glass was reduced, and the low-stress stepped optical glass which was easy to install and adjust was designed. SolidWorks software was used to calculate the stress difference of the two structural forms under the appropriate pre-tightening force and the internal and external pressure difference of one atmosphere, and Abaqus software was used to analyze the influence of temperature on the optical glass during the wind tunnel test. The results show that the pressure difference has little effect on the strength of the glass observation window, and the stress of the stepped optical glass is less than that of the original structure; the sudden drop of temperature under high Mach number and pressurization will cause the stress concentration in the middle of the observation window.