A doubly-sealed water pump comprises a shell, a swash plate, a first piston, a second piston, a third piston, a pressure release regulating valve, a water outlet check valve, a water outlet valve, a water inlet valve, discharge holes, a piston push plate and a thrust bearing. The swash plate, the first piston, the second piston, the third piston, the pressure release regulating valve, the water outlet check valve, the water outlet valve, the water inlet valve, the discharge holes, the piston push plate and the thrust bearing are positioned in the shell, one end of the swash plate is fixed onto the shell by an oil seal cushion, the other end of the swash plate is connected with the piston push plate by the thrust bearing, the front end of the first piston is embedded in the piston push plate, the rear end of the first piston is connected with the water outlet check valve, front ends of the second piston and the third piston are embedded into the piston push plate, rear ends of the second piston and the third piston are connected with the water outlet valve, the water inlet valve is communicated with a water inlet hole and the water outlet valve, the water outlet valve is communicated with a water outlet hole, the pressure release regulating valve is disposed above a high-pressure water outlet pipe zone, one discharge hole is arranged among the first piston, the second piston and the third piston, and the other discharge hole is arranged among the second piston, the third piston and the water inlet valve. The doubly-sealed water pump is a triangular arrangement structure, and double sealing effects are realized.