Tiltrotor which combines the advantages of helicopters and fixed wing aircraft, is a key direction for future aviation equipment development. This article focuses on the key component of tiltrotor - pylon conversion actuator. The tilting actuation principle of tiltrotor is introduced, the advantages and disadvantages of V-22 and BA609 pylon conversion actuator configurations are analyzed and compared, and the key technologies of pylon conversion actuator of tiltrotor are discussed, including power summing technology, double-layer telescopic ball screw technology, ball screw end shock damper technology. The power summing technology can realize double-system synthesis by speed summing or force summing, which is the key to improve the reliability of pylon conversion actuator. Double-layer telescopic ball screw can effectively shorten the volume after the actuator is retracted, reduce the space on the aircraft nacelle, and greatly improve the safety of the actuator; Shock damper is a means to effectively restrain the impact caused by the screw end collision, which is very suitable for linear output mechanism such as ball screw.