The invention discloses an automatic balancing valve which comprises a valve body, and two hydraulic control one-way valve assemblies, two directional control valve assemblies and two pressure controlvalve assemblies are arranged on the valve body; one end of the hydraulic control one-way valve assembly is connected with a liquid inlet chamber and a liquid return chamber of a system, and the other end of the hydraulic control one-way valve assembly is communicated into one of balancing cylinders; one ends of the directional control valve assemblies are respectively communicated into one of the balancing cylinders, a control chamber of the directional control valve assembly and a liquid inlet chamber of the pressure control valve assembly; and a liquid outlet chamber of the pressure control valve assembly is communicated with the liquid inlet chamber and the liquid return chamber of the system. The invention has the advantages of simple structure, easy processing and convenient dismounting and maintenance, the position of the balancing cylinders can be locked while the pressure are free, the cylinders float while in pressure, the stability of posture adjustment of hydraulic brackets is achieved, and the safety operation of the brackets is ensured.