By studying on Pingwang water level and Mishidu tide level Hydrograph in Taihu Basin and their impacting factors, the concepts, ranges, moving and the decomposition as well as the reconstruction of the averaged tide level hydrograph are put forward. With the method of the statistics correlation, the forecasting models of the Pingwang water level and Mishidu tide level hydrograph are developed. Using the measuring data in flood season from 1996 to 1999, the forecasting model are calibrated, and the results of the calibrating are satisfactory. The methods proposed in this paper are useful to the flood forecasting and controlling in Taihu basin.