The invention relates to a control valve. The control valve is characterized by comprising a valve block; the valve block is provided with an oil inlet, an oil return port, a first working oil port, asecond working oil port, a third working oil port and a fourth working oil port; a first reversing valve element and a second reversing valve element are slidingly arranged in a first channel and a second channel; a first main control cavity, a first oil return cavity, a second main control cavity and a second oil return cavity are formed on the two sides of the first reversing valve element andthe second reversing valve element; a first spring and a second spring for keeping left moving tendency of the first reversing valve element and the second reversing valve element are arranged in a first secondary control cavity and a second secondary control cavity; a first end cover, a second end cover, a third end cover and a fourth end cover are arranged on the valve block for blocking the first channel and the second channel; a first piston is arranged in the second end cover to form the first secondary control cavity; a second piston is arranged in the fourth end cover to form the secondsecondary control cavity; the valve block is provided with a first overflow valve and a second overflow valve for controlling the first reversing valve element and the second reversing valve elementto move to the right side, and an one-way overflow valve for communicating the second working oil port with the fourth working oil port; and when the control valve works, the first overflow valve, thesecond overflow valve, the one-way overflow valve, the first spring and the second spring control the first reversing valve element and the second reversing valve element to automatically reverse. The control valve is simple in structure and low in cost, can automatically finish automatic control of a double-cylinder hydraulic overturning plough, and is high in automation degree.