In order to analyze the risk of disastrous flood in the Xijiang River basin, this paper studied the encountering law of thefloods at the Wuzhou Station from the main stream and tributaries in the aspects of flood composition, encounter time and floodpeak return period based on the hydrological analysis method. The results show that the proportion of average daily flow for 15floods at the Wuzhou Station from the rivers of Hongshui, Liujiang, Yujiang and Guijiang are 32.31%, 40.57%, 13.19% and 9.13%,respectively. The floods from the rivers of Xijiang, Liujiang, Guijiang and Yujiang mainly concentrate in June to August, June toJuly, May to July and July to September, respectively. The floods from the rivers of Hongshui and Liujiang encounter frequently,while the flood encounter flood grade of the Yujiang River and Guijiang River is small. The disastrous floods at the WuzhouStation are composed of 3 kinds of flooding encounter types, which are the whole basin flood, Hongshui River-Liujiang River-Guijiang River flood, and Liujiang River-Yujiang River-Guijiang River flood. The recurrence periods of them are greater than 100,50 and 20 years in turn, as reveals the significant increase of flood recurrence period at Wuzhou station after the flood encounterof the main stream and tributaries in the Xijiang River. The results can provide hydrological analysis reference for flood controland disaster mitigation in the Xijiang River basin.