The invention discloses a gate pressurizing water stopping method and device for an ultra-high head. When a pressurizing water seal (H) is connected with an upper level of a gate through a pipeline, the gate pressurizing water stopping device for the ultra-high head is arranged between the pressurizing water seal (H) and the upper level of the gate, and meanwhile the device is connected with a downstream side of the gate through a pipeline. Therefore, pressure acting on the pressurizing water seal (H) can be controlled through the device, so that the pressure acting on the pressurizing water seal (H) is kept consistent with system set pressure of the gate pressurizing water stopping device for the ultra-high head. According to the device, pressure control over a back side pressurizing cavity of the gate pressurizing water seal can be carried out; at the initial work stage of the gate water seal, the water filling pressure value can be properly turned down, and the water filing pressure value is properly increased along with prolonging of the work time limit of the gate water seal to slow down the stress relaxation and creep rate of a water seal material and prolong the working life of the pressurizing water seal; and when slight water leakage happens to gate water stopping, the water filling pressure value can be turned up, and the water stopping effect is enhanced.