A guide microscope is an important part of a certain photoelectric automatic tracking system, and the angle informations acquisition, processing and transmission are the keys for using the guide microscope. According to the application requirements, a kind of angle information processing system of the guide microscope based on STM32 is designed. This system uses the high-performance STM32F103 as the control core and realizes the angle information acquisition, display and transmission by photoelectric encoders, OLED display and RS-485 bus. Then, the hardware design and software debugging are further explained, that it has the simple circuit and convenient development. The running results show the design has the stable and reliable performance. It can meet the requirements.