Abstract: Angle measurement accuracy plays an important role in photoelectric theodolite positioning and tracking. In order to further improve the accuracy of photoelectric theodiolite, the angle measurement errors were analyzed. Based on the overall design of photoelectric theodolite, the error sources of angle measurement accuracy which effect data acquisition, transformation and synthesis were found, and a detailed analysis of the size and properties was made. This paper first found out the main error sources by analyzing the working principle and structure of photoelectric theodolite. Then, it analyzed and calculated the rack system error, angle measurement system error, electrical system error, off target error, atmospheric refraction correction error, and distributed the error for each system. Finally, this paper calculated the root mean square of photoelectric theodolite-s angle measurement accuracy. The results show that the careful design, machining, testing and correcting could reduce and even ignore errors, but the infl ence on the angle measurement accuracy of the rack system error, angle measurement system error and off target error is still significant; it is possible to develop the photoelectric theodolite accuracy of spatial point less than 2 under the current level of technology.