The foundation pit flooding accident of the Jiangsu Disability Rehabilitation Center project was caused by the improper previous dewatering plan design and quality control of dewatering construction. In depth analysis of the stratum data about the project location during the accident handling process showed that this area is a typical dual geological structure of the Yangtze River floodplain where the main aquifer is the thick sand layer. With fully consideration of the characteristics of the aquifer such as great thickness and large permeability coefficient in this area , the number and depth of dewatering wells was properly planned. Through abandonment of unqualified dewatering wells, and strict control of the construction quality and operation management, the water flooding accident at the foundation pit was successfully resolved. This article details the accident history and treatment process so as to provide useful experience for similar projects.