A backstepping sliding mode control algorithm was proposed for the position and attitude feedback control system of a foldable coaxial reverse-propeller UAV. The dynamic model of the UAV is established by analyzing the flight state of the UAV. The attitude and position control algorithm of the folding coaxial dual-rotor UAV is designed by using the backstepping sliding mode control algorithm, and the flight test experiment is carried out by developing the test prototype. Experimental results show that, compared with the traditional cascade proportional-integral-derivative (PID) control algorithm, the proposed backstepping sliding mode control algorithm can effectively improve the flight stability.