Disclosed is a pumping method of a large-diameter horizontal pressurized long dewatering well for inexhaustible pumping strata. Clay layers and sand soil layers are determined according to construction positions of foundation pits, horizontal holes are drilled in the sand soil layers with a drill rig with simultaneous casing, and after the designed depth is reached, horizontal wells are placed, the horizontal wells are located above the junction of the clay layers and the sand soil layers, and the horizontal wells comprise drain pipes and air ducts, the drain pipes and the air ducts are located at the same elevation, each air duct is located between the two drain pipes, and the air duct is connected with the air pipe of the air compressor to deliver and pressurize, so as to facilitate water in the strata of aquifer to gather into the drain pipes.