Based on Xin＇ anjiang model, a kind of flood forecasting and real-time correction method for Wuxi River Basin is explored. Based on the characteristic of watershed runoff yield and concentration, the watershed subdivision is done by taking rainfall stations as centers. To simulate the time-varying characteristics of watershed runoff concentration, the flow time of overland flow concentration of each sub-basin is used to control watershed runoff concentration process. Aiming at reducing the error of initial state and calculation, the real-time correction method of optimizing early free water storage time interval by time interval is presented and the runoff coefficients of predictive flow processes are utilized to make rationality verification. The results show that the presented flood forecasting and real-time correction method for Wuxi River basin is reasonable.