The influence of icing on the aerodynamics of aircraft is a focal point of aircraft icing research contents. An aircraft model on the background of a typical geometry of large passenger aircraft is constructed. By the RANS method, the complex flow field structure and aerodynamic characteristics of the aircraft under condition of wing icing are studied. The research results show that the wing icing mainly affects the aerodynamic characteristics near the stall point of the background aircraft, and the departure of the airfoil flow separation is greatly in advance and the separation ladder disappears completely, which is the direct reason for the deterioration of the stall characteristics and the reduction of the aerodynamic boundary. The study can provide full support to deeply understand the aerodynamic flow mechanism of the effect of aircraft icing on aerodynamics, and provide a basis to analyze aerodynamic characteristics and flight dynamics of large aircraft after icing.