Abstract:Electro-hydraulic proportional valves are one kind of hydraulic control components, among which the pressure, flow rate and input current are realized in proportion in the hydraulic system, through the solenoids of valves manipulated in correspondence according to input signals, then causing displacement of the cores of valves and varying of the throttling orifice. These components have become important hydraulic composing parts, and have wide applications in the fields of engineering, taking the advantages of the large output force, fast response and compact design, and agility of their electronics control. The origin, development, structure and working principles, as well as the characteristics of performance of several new typical electro hydraulic proportional valves were discussed and analyzed. Finally the development and applications of the valves were previewed.