In this study, we analyzed the period change characteristics of three precipitation series in a year, flood season (from April toSeptember) and non-flood season (from October to March of the following year) based on the methodology of wavelet transformation. The resultsshow: (1) The periods are different in various regions in the Pearl River Basin. The Pearl River Basin can be categorized into three regions bythe distribution characteristics of the period. The main period scales are as follows: 6 to 8 years, 12 to 14 years, and 20 to 21 years. (2)The pe -riod of the annual and flood season precipitation is mainly an inter-annual change, and the period distribution between the two is consistent.The inter-decadal variation of non-flood season period is the dominating pattern, and there is a large difference between the period of nonflood season precipitation and that of the annual and flood season.