H142X hydraulic water level control valve is a hydraulic control valve that automatically controls the height of the water tank and water tower. When the water level drops more than the preset value, the float valve opens, the pressure of the upper chamber of the piston decreases, and the pressure difference between the piston up and down is formed, and the valve disc opens under the action of this pressure difference for water supply operation: when the water level rises to the preset height, the float valve is closed, the pressure of the upper chamber of the piston continues to increase, and the valve disc closes to stop the water supply. In this way, the liquid level is automatically controlled at the set height to realize the automatic water supply function.