Ultra-smooth surfaces are widely used in the field of optics, and the polishing method is an important component of super-precision technology. Firstly, the characteristics of ultra-smooth surfaces are introduced, and the classification and comparison of the polishing methods are made. It is shown that the non-contact method is the ideal ultra-smooth surface polishing technology. Then the existing ultra-smooth surface polishing technologies are summarized, and the machining mechanism, precision and application spectrum are expounded. At last, the gap of ultra-smooth surface polishing technologies at home and abroad is present, and the trend of the technology is described.