The prediction of surface subsidence after underground coal mining is of practical significance for land planning and utilization in subsidence area. For a case study, the deformation and failure of a drainage boat pond caused by an underground coal mining-induced subsidence are investigated (the drainage boat pond is located in the Nanyang Lake Farm, Jining City, China). A mining subsidence prediction model suitable for the irregular coalface is established using the improved probability integral method to analyze the subsidence parameters. A numerical model of the boat pond deformation is established to simulate the stress, displacement, and plastic zone distribution of the boat pond. The boat pond deformation prevention structure is proposed from the prospects of pond bottom, pond slope, and pond slope protection. Moreover, the reinforcement of drainage boat pond is achieved in five steps. Finally, the deformation and failure state of the reinforcement boat pond under coal mining subsidence is simulated, and the rationality of the reinforcement measures is also verified by a field investigation. The research results have an important practical significance for water resource protection and structure construction in underground coal mining-induced subsidence.