*† ‡ Ice accretions over critical aerodynamics surface cause significant degradation in aircraft performance and handling qualities. In this paper, ice accretion on the leading edge of the NACA 0012 airfoil is predicted using CFD method. A four -order Runge -Kutta method is used to solve the droplet trajectory equation. Ice shape is determinated with assumption that all droplets freeze at their points of impact and that the ice grows in the direction normal to the surface. Numerical simulations using the Reynolds -averaged Navier -Stokes equations are conducted to investigate the ef fect of ice shapes on the aerodynamics performance. Designing three different icing models, sharp -angled ice and blunt -nosed ice and double horn ice , the flow field of a four -element airfoil are calculated and analyzed. Using a multi block grid technique, we generate computational grids as shown in Figures for the four element airfoils. We solve the N -S equations with a conventional algorithm, which includ es cell -centred finite volume method and Runge -Kutta time -stepping scheme , and complete the solution of the N -S equations by introduc ing the B -L algebraic turbulence model . Using the above methods and techniques, n umerical results are presented. The computational results are in good agreement with the available experiments data show preliminarily that our method of icing accretion model and flow field numerical simulation is feasible .