After configuration size and combing type of aerial electro-optical equipment have been confirmed, thickness dimension is critical to its imaging performance. The window designing subject was described and analyzed from three aspects: design variables, combing types and applied loads, and the design goal of plane window thickness based on structural rigidity and root mean square (RMS) wavefront error was determined. Based on the first order structural resonance frequency and the RMS wavefront errors under temperature and pressure loads effects, the window thickness dimension range of 11.9 mm to 18.4 mm was quantified and solved. Integrated analyzing process was proposed aiming at window assembly performance in synthetic conditions. The first order structural resonance frequency of optical window assembly is 151 Hz, the RMS wavefront error is less than 1/10 reference wavelength with effects on composite load, such as flow field, gravity and vibration in operation. The test results show that the RMS wavefront error of optical window is less than 0.07 reference wavelength, and the images of vibration and flying test are stable and clear, which verifies that the design and analysis method of window thickness dimension is right and effective.