Belong to the plain river network area, There are interconnected waterways and the flow directions can not be determined in the Taihu Basin. There is no control section in the basin, and the design flood is obtained according to the runoff model which using the design storm to calculate indirectly. Therefore, the results of design would directly affect the flood control plan - ning, engineering design, risk planning of the basin, which is a very important basic work. This paper carried out a revised design storm calculation of Taihu Basin, which was compared with the flood control planning. Besides, according to different space alloca - tion of design storm, this paper carried out the rationality analysis of the results between the method.