Abstract: In view of the problems existing in the high precision forming of the special-shaped light window, the characteristics of the light window and the principle of the forming technology were introduced. Experimental researches were carried out from 4 key problems, such as the mirror protection, the position tooling design, the size measurement and compensation algorithm, the optimization of the milling parameters and so on. And the micro-stress precise lossless forming of the special-shaped light window was realized. Results show that the linear error is less than 0.03 mm, the two-dimensional angle error is less than 20″, the angle error of the inclined plane is less than 1.2′, and the surface defect is less than Ⅳ, which can meet the requirements of the stealth aircraft for special-shaped light window.