In order to realize the miniaturization of spaceborne photoelectric encoders, minish the sizes and weights of the spaceflight equipment effectively and to satisfy the requirement of the cold copy of photoelectric converting circuits, a signal process system is designed for the spaceborne photoelectric encoder with dual-reading system.Firstly, the process methods of the coarse and precise code signals are presented for the spaceborne photoelectric encoder with dual-reading system and the miniaturized and reliable design of the signal process system is described.Then, the accuracy of the spaceborne photoelectric encoder with dual-reading system is analyzed based on the error sources and distribution characteristics.Finally, using a 23-bit high precision photoelectric encoder as the angle standard, the accuracy of the designed photoelectric encoder is tested based on a comparison method.The experiment results show that the resolution and the accuracy of the photoelectric encoder with dual-reading system are 20″ and less than 30″,respectively.By applying to practical projects,the process system has satisfied the technique requirement of the spaceborne equipment.