High density of driving power, fast response, high rigidity and high-precision are the advantages of hydraulic servo system, so it is widely used in aerospace. All of flight actuator and transmitting systems of today´s aircrafts are nearly driven by hydraulic systems. With the development of aircraft, especially of military aircraft, more demands are proposed to aircraft hydraulic system. In this paper, main developmental trend of airborne hydraulic system, especially for military aircraft, is summarized, and some research works on aircraft hydraulic systems in domestic and overseas are introduced. Light weight, small size, high-pressure, high power, variable pressure, intellectualization, integration, redundancy techniquue, and so on are the main trend of development of future aircraft hydraulic system. Especially, high-pressure, variable pressure hydraulic intelligent pump source system is very important for the development of future aircraft.