Roof prism has the functions of turning light path, image rotation, directional reflection, shortening system light path and so on, which is widely used in aiming systems. In the optical system of visual optical instruments, ridge prism is often used to transform the image in order to obtain complete consistent images. Compared with other prism or lens groups, roof prism has the advantage of small volume. High precision roof prism has high requirements in its angle error, surface error and surface roughness. How to obtain high precision and reduce production cost is a difficult problem in the optical manufacturing industry in recent years. A polishing process to control the accuracy of ridge angle is mainly introduced, in which the way of light glue plate, the influence of ridge surface shape on ridge angle and the rework method of ridge surface are analyzed, and the control of ridge angle accuracy of high-precision ridge prism is expounded.