The invention provides a tiltrotor controlled by a double-propeller vertical duct. The tiltrotor, using the design of parallel twin-rotor and conventional aerodynamic configuration, consists of a fuselage, straight wings, rotors, a nacelle, an aileron, a vertical empennage, a rudder, an elevator, a horizontal empennage, a duct end cover, a vertical duct, an undercarriage, a power and decelerationsystem, a propeller power input shaft, a lower propeller, an upper propeller, louver-type slipstream sheets, a propeller gearing and collective-pitch controlling device, a propeller gear box supporting structure, a duct end cover driving device, a duct end cover motion slide rail and a slipstream sheet controlling device. Compared with the cyclic pitch control mode, the tiltrotor of the inventionsimplifies the operations during the vertical flight and the flight conversion and improves the reliability by using the structure of the double-propeller vertical duct to control the vertical flightand the conversion of the flight mode, and the tiltrotor has the advantages of long control force arm, high control efficiency and simple structure. Therefore, the tiltrotor constitutes a novel aircraft with significant development potential and promising future.