The invention discloses a folding-wing unmanned aerial vehicle. The folding-wing unmanned aerial vehicle comprises a vehicle body, a tail wing and airfoils, wherein the airfoils are connected with the vehicle body by folding devices; each airfoil comprises a base plate, an airfoil body and a sliding plate; sliding chutes are formed in each base plate; a guide posts is arranged in each sliding chute; a first spring is arranged on each guide post; a threaded hole is formed in the middle of each base plate; a plurality of shallow slots are uniformly distributed in each base plate by taking the threaded hole as the center; two rotating wheels are separately arranged at two sides of the top of each sliding plate; two sliding blocks are separately arranged at two sides of the bottom of each sliding plate; a through hole is formed in each sliding block; each sliding block is arranged in the corresponding sliding chute in a sliding way; and the through hole of each sliding block is formed in the corresponding guide post in a penetrating way, so that one side wall of the sliding block props against the corresponding first spring. According to the folding-wing unmanned aerial vehicle disclosed by the invention, grazing angles of the airfoils can be automatically changed according to the difference of flying speeds; when the flying speed is high, the grazing angles of the airfoils are increased, so that the flying resistance is reduced, and the flying efficiency is improved; and in addition, the airfoils are effectively protected from being damaged when collision occurs.