LY-M4 , four-rotor unmanned aerial vehicle (UAV) system ,is one mini type UAV which can be quickly dismounted. Its fuselage structure is made of 100% carbon fiber material. Rack, upper cover, supporting arm, landing gear, motor bracket, etc. are all light-weight structure design ,among which four of arms adopt plug-in structure, fast storage and portable, small storage size as well as easy to transport. The system's take-off load weight is less than 4kg, with largest overall dimension less than 1100mm. It only takes a fewminutes to unfold its fuselage, also only a few moments to wait GPS satellite to positioning once powered-on, which is actually one small UAV operation aircraft with wide range of applications, and can be widely used in film and television aerial, aerial reconnaissance, anti-terrorism, forensics, geological survey, remote sensing mapping, communications relay, environmental protection,meteorological exploration, disaster monitoring, aerial surveying ,public fire security, and other industries as well as fields.