Outdated coal mining technologies involve considerable mine water resource waste. For coal mines located in water-starved western regions of China, this jeopardizes the sustainable coal mining development, local eco-environment, and agricultural production. Coal mine underground reservoirs furnish conservation and cyclic utilization of water resources in the coal mining process. The weakest links of underground reservoirs are artificial dams that are prone to frequent occurrence of water seepage and instability failures. Aiming to explore the deformation rules of artificial dams under fluid–solid coupling action, this study developed a nested multi-coupling test system comprising a model shelf, a mine pressure simulation device, a water pressure simulation device, and a monitoring system, The maximum size of the model shelf is 1400 mm * 1300 mm * 200 mm. The mine pressure simulation device was composed of static-load and vibration-load oil cylinders of various sizes. A servo motor mainly controlled the water pressure device; with a water pressure sensor and high-precision flowmeter, water pressure could be accurately adjusted. By taking the underground reservoir in the Wulanmulun Coal Mine as an example, the deformation failure characteristics of the MB-1 dam under fluid–solid coupling conditions were simulated to validate the reasonability and feasibility of the developed system. The obtained experimental results indicated that the artificial dam damage was induced by increased mine pressure, leading to shear compression failure. The artificial dam underwent plastic deformation at a water pressure of 11.43 kPa, accompanied with the generation of microfractures, which rapid propagation under vibration loading violated the dam’s stability.