H142X hydraulic water level control valve is a hydraulic control valve which can automatically control the height of water tank and tower. When the water level drops beyond the preset value, the floating ball valve opens, the pressure of the upper chamber of the piston decreases, and the pressure difference between the upper chamber and the lower chamber of the piston forms. Under this pressure difference, the valve disc opens for water supply operation. When the water level rises to the preset height, the floating ball valve closes, and the pressure of the upper chamber of the piston keeps increasing, which roughly causes the disc closing and stopping water supply. This reciprocating automatic control of the setting height of the liquid level can realize the function of automatic water supply.