Abstract:The regional rainstorm of Sichuan Basin is classified using the data from meteorological stations in Sichuan Basin, NCEP/NCAR reanalysis data, NOAA SST data, snow days of Tibet Plateau, and the method of MTM SVD (multi taper method singular value decomposition). Not only the characteristics of spatio temporal variation but also the previous signal is discussed. The results show that the regional rainstorm of Sichuan Basin can be divided into three types, which are the west basin, northeast basin and south basin respectively. The most significant interannual variation is the quasi 3 year cycle which reflects the abnormal circulation process of west basin type with the weak adjustment strong pattern. The quasi 16 year cycle is the obvious interdecadal signal which embodies the exception evolution of the northeast basin and south basin. Through the analysis of cooperative change, it is found that the ENSO event and snow cover days in the previous winter are the strong precursor signal in the quasi 3 year cycle. In the quasi 16 year oscillation process, the PDO (Pacific decadal oscillation) acts as a previous signal of the northeast basin type and south basin type.