As a common deicing system for turboprop aircraft, it is of great significance to evaluate the influence of deicing airbag on the aerodynamic characteristics of the aircraft. Based on the aerodynamic deicing system installed on one aircraft, simulating the aerodynamic characteristics when the deicing airbag working by using the CFD method, and analyzing the influence of the simplified deicing airbag model on the calculation results. The results suggest that: with the height of the deicing airbag increases, the effect on the aerodynamic characteristics of the aircraft becomes more obviously, the stalling angle advanced by about 10 degrees, the maximum lift coefficient lost nearly 60%, and the maximum lift-to-drag ratio decreased by about 2.9. Influenced by the expansion of the deicing airbag, a flow along the wingspan appears in the leading edge, and the length of separation zone is the same as the deicing airbag. The pressure distribution at leading edge is oscillating because of the expanded deicing airbag, so the whole airfoil’s pressure distribution is further affected. Besides, with the height of the simplified deicing airbag increases, the stalling angle advanced by about 1 degree, the maximum lift coefficient lost nearly 21%, and the maximum lift-to-drag ratio decreased by about 2.2. All results above show that the aerodynamic performance of the aircraft in flying tests is decreased due to the different working conditions of the deicing air bag.