The types and application status of precision reducers for robots were reviewed. The characteristics and research progress of RV reducer, harmonic planetary reducer and Sumitomo reducer were emphatically discussed. The accuracy problems of RV reducer, harmonic planetary reducer and cycloid pinwheel reducer were analyzed. It was pointed out that the development direction of precision reducer for robot was to study new reducers with higher transmission ratio, higher efficiency, smoother transmission, high accuracy and high performance. At the same time, the study of new reducer was the direction of future development.