Abstract. Tilt-rotor aircraft can be used in various fields because they have the capabilities of the ver-tical take-off and landing and the high-speed cruise flight. In the present study, the flow analysis of atilt-rotor aircraft is conducted at various tilt angles. The lift and drag forces of the tilt-rotor aircraft areobtained and the wakes by the rotor-blade are visualized. The result shows that the rotor-blade affectsthe lift force in a hovering mode and the main wing has an influence on the lift force in a cruise mode.Additional thrust is required at the tilt angle of around 40 degree due to the least lift force. The dragforce is dependent on the rotor-blade at overall tilt angles. The minus drag force appears between thetilt angles of 90 degree and 55 degree. Also, the drag force is dramatically increased at the other tiltangles. The wake by rotor-blade affects the flow around the fuselage of the tilt-rotor aircraft at the tiltangles of 75 degree and 60 degree. Key Words:Tilt-Rotor Aircraft(틸트로터 항공기), Flow Analysis(유동해석), Tilt Angle(틸트각), LiftForce(양력), Drag Force(항력)