The invention provides a hybrid power tail sitting type vertical takeoff and landing long-endurance unmanned aerial vehicle and a flight control method thereof. The unmanned aerial vehicle comprises a fuselage, wings, a main driving motor, propellers, a piston power ducted propeller and tail wings mounted on a duct. According to the invention, two sets of power systems, namely a motor and a piston engine, are adopted; in a vertical takeoff and landing stage which is short in time and requires large power, the motor serves as driving power, the advantage of high power-weight ratio of the motor can be fully exerted, and thus the weight of the power systems is reduced; in a cruising flight stage, the tail piston engine and the ducted propeller system driven by the tail piston engine drive the unmanned aerial vehicle to fly forward, and the piston power and the ducted propeller system can be selected and designed according to the optimal cruising state without considering the vertical takeoff and landing state, so that the fuel consumption rate of the cruising state can be effectively reduced; in combination with high-aspect-ratio wings, long-time flight of the unmanned aerial vehicle can be ensured; and meanwhile, because the weight of the power systems is reduced, the empty weight ratio of the unmanned aerial vehicle can be reduced, and the loading capacity of the unmanned aerial vehicle can be effectively improved.