Angular encoder is widely used in precise machine measurement of angular position and the speed of shaft. The parameter of the mechanical structure is one important target that influencing the performance of the angular optical encoder, which is the basic ensure for the accuracy of the angular encoder. In the practical application, because of the hostile work environment, for example, the factors of temperature, vibration and noise, would make great interference to the measurement performance of the angular encode，among these, vibration took the most percent. Therefore, the interference of the measurement accuracy of the angular encoder under vibration was studied, which made contribution to improve the structure performance of the angular encoder, and provided the reference in theory that improved the accuracy of measurement of the angular encoder in the post processing. By choice of the angular encoder as the study object, the work principle of it is introduced, and the characteristics of the interference of the accuracy of the angular encoder under vibration were studied.