The invention discloses a folding wing unmanned aerial vehicle for the constructional engineering. The folding wing unmanned aerial vehicle comprises a fuselage, an empennage and wings. The wings are connected with the fuselage through folding mechanisms, the wings comprise baseplates, wing bodies and sliding plates, first chutes in which guide pillars are arranged are formed in the upper parts of each baseplate, first springs are arranged on the guide pillars, a threaded hole is formed in the middle position of each baseplate, and multiple shallow slots uniformly distributed by taking each threaded hole as the center are formed in the corresponding baseplate; turning wheels are arranged on both sides of the top of each sliding plate, a first slider is respectively arranged on both sides of the bottom of each sliding plate and provided with a through hole, the first sliders are installed in the first chutes in a sliding way, and the through holes of the first sliders are arranged on the guide pillars in a penetrating way, so that one side walls of the first sliders are propped against the corresponding springs. According to the invention, the grazing angles of the wings can be automatically changed according to different flight speeds, flight efficiency is improved, and the wings can be effectively protected from being damaged in a collision.