Research on rainfall distribution is of basic scientific significance for regional hydrological modeling, planning and management of water resources, flood and drought disaster assessment and improvment of ecological environment. This paper mainly commentaried research progress of spatial interpolation of rainfall data from the visual angle of methodology on a microscopic level. Firstly, it separately discussed advantages and disadvantages of the deterministic method and the spatial statistics method used to research spatial interpolation of rainfall data, discoursed upon the scientific basis of information entropy theory and methods, and studied the spatial interpolation of rainfall, finally prospect the feasibility, rationality and technical characteristics of information entropy method.