The invention discloses a double-water-storage-chamber high and low pressure water conversion system and method for mine cooling, and belongs to the technical field of depressurization of mine high pressure water. The double-water-storage-chamber high and low pressure water conversion system is mainly constituted by a high-pressure water storage chamber, a first one-way valve, a pressure converter, a high-pressure conversion valve, a low-pressure conversion valve, a three-way switching control valve, a second one-way valve, a low-pressure water storage chamber, a piston connecting rod assemblyand matched pipelines which are connected between a ground refrigeration station and a tail end air cooler. High-pressure cold water conveyed from the ground refrigeration station to the downhole isdepressurized, thus the pressure of the cold water meets the pressure-bearing requirement of the tail end air cooler of the coal mine downhole, and the purpose of lowering the investment cost is achieved; meanwhile, low-pressure hot water circulated back from the tail end air cooler is pressurized and conveyed to the ground through a pipeline; and closed circulation of water returning from frozenwater to the hot water of the system can further be achieved.