According to the demand of high precision optical system and the present research achievements, a large curvature radius measurement system is developed based on the interferometric measurement. Error factors affecting the measurement precision of the developed system are analyzed, and a mathematical model of error distribution and an error distribution tree of the measurement system are established based on the error theory and the system composition. Combined the actual usage requirements, the target uncertainty of the measurement precision of the system is distributed and then combined. Results show that the standard uncertainty is 2.49 μm, and it less than 2.5 μm which is the target uncertainty required by the system. The distribution result is used as the input index for the design of subsystem structures. Measures that can improve the measurement precision of curvature radius are proposed and summarized. According to the error distribution result, a system for measuring large curvature radius which can satisfy the using requirements is designed.