A light unmanned aerial vehicle composite material structural system with the high maintainability comprises a fuselage (1), a wing (2), upper empennages (3), lower empennages (8) and flaps (28). Thewing (2) is located in the middle of fuselage upper skin (12) to be fixed to wing and fuselage connecting frames (15), and the wing (2) is provided with the flaps (28); and the upper empennages (3) are installed at the tailcone section of the fuselage upper skin (12) and fixedly connected with empennage installation frames (16), rudders are installed on the upper empennages (3), and the lower empennages (8) are installed on tailcone lower skin (6) and fixed to a lower empennage installation frame (7). According to the light unmanned aerial vehicle composite material structural system, except for a very few of structures bearing impact loads, all main force bearing structures adopt composite materials, compared with an original structure technology of the same type of unmanned aerial vehicles, the material characteristics of the composite material are utilized ingeniously, the bearing and functional requirements of a small high-speed unmanned aerial vehicle full-composite-material structure are met, the cost is low, and the maintainability is high.