Abstract: The method of comparing the shape of the ice by the influence degree on the aerodynamic characteristics is proposed. The degree of similarity of ice shape is considered to be mainly depended on two variables, the first variable is the degree of similarity of the geometric characteristics of the ice shape, and the second the degree of difference between ice shapes. The method of ice shape similarity is verified by calculating the impact of different ice on the aircraft's aerodynamic performance with CFD tools. The aerodynamic characteristics with different ice shapes for the NACA0012 airfoil are simulated and analyzed. The proposed method of ice shape similarity is verified, and influence degree of the aerodynamic characteristics is more closely when ice shapes are more similar.