Abstract: The influence of propeller slipstream on aerodynamic characteristics of conventional layout turboprop aircraft is studied at large attack angle by using propeller aircraft dynamic simulation test. The dynamic simulation test is curried out in FL-9 wind tunnel of Aerodynamics Research Institute of AVIC. The propeller is driven by servo motor. The test angle of attack range is 0°~50°, and the wind speed range is 30~50m/s. The conventional single strut is used at the normal attack angle test, while the special prebending strut is used at the large attack angle test. The coupling effect of flat tail deep install and propeller slipstream is studied detailedly. The test results show that the propeller slipstream increases lift and drag forces of the test model, and decreases the longitudinal static stability, and these features also exist at large attack angel test. In addition, the slipstream will make the deep stall effect of flat tail worse, and the flat tail will be harder to get out of stall when the flat tail entering the coupling influence area of slipstream and wing wash flow at the large angle test condition. That means the range of attack angle effected by deep stall will be larger and flat tail deep stall effect is aggravated.