In order to minimize volume, lighten the weight of a spaceflight camera effectively and satisfy the requirement of cold copy , the design for spaceborne absolute photoelectric encoder of dual numerical system is put forward in this paper. Based on the requirements of the spaceflight camera, the miniaturization design is applied to absolute optical code disc; Then, a dual numerical reading slit disc and a numerical reading system are developed according to the characteristic of code disc; finally, the precision test is implemented on the spaceborne absolute photoelectric encoder with dual numerical reading system. The experimental result shows that the photoelectric encoder in outline dimension of 50 mm×32 mm, weight of 150 g can offer its resolution of 20″and precision lower than 30″. The encoder has the function of cold copy for numerical reading system, and shows its advantages of small volume, light weight and high resistance,which can meet the requirements of spaceflight camera.