Abstract: Using the dynamic simulation and PIV test technology for propeller aircraft, research on the propeller slipstream effect on the longitudinal aerodynamic characteristics of the conventional layout twin-engined turboprop aircraft is conducted. Wind tunnel test is used to study the slipstream effect on longitudinal characteristics as the propeller position changes, such as the aircraft lift and drag characteristics, moment characteristics and horizontal tail downwash. PIV test is used to setting out typical section of aircraft components, mainly focus on the position conformed by slipstream wind tunnel test. Slipstream has bad effect especially on lift and drag characteristics when the propeller position sinkage. Both extending the propeller position forward and changing the propeller installation angle can improve the aerodynamic characteristics of the aircraft, while the aircraft lift characteristic is improved obviously especially around the stall angle when the propeller position extends forward.