In order to meet the high quality requirements of the production and running of the cascade water conservancy hub project on the upper Yangtze River, the Error Analysis and Correction System of Numerical Forecast Products of the Upper Yangtze River Basin is researched and developed. The system implements the function of statistical analysis and comparison of numerical forecast products’ errors including T639, ECWMF, and Japan models. The objective correction numerical products of prediction and feature field forecast can be automatically generated through the system, as well as the output of the refined numerical forecast products of precipitation for the upper Yangtze River by using the graphical subjective correction platform of forecast products. The system provides support to the weather forecast service with high precision for the comprehensive and effective using of various forecasting products. The system has been put into operation in the Three Gorges Cascade Dispatching Communication Center and performed satisfactorily in the recent heavy rain forecasting service, which runs steadily, is convenient to operate, and has good correction effect.