Ice accretion on aircraft components is an enormous threat to flight safety. In this paper, ice accretions on the leading edge of the NACA 0012 airfoil and the NLR 7301 multi-element airfoil with flap are predicted using the icing code developed by us. This code mainly contains five modules which are grid module, airflow module, droplet module, heat module, and boundary reconstruction module. The effectiveness and robustness of this code are tested by executing the five modules orderly and repeatedly. The Spalart-Allmaras one-equation turbulence model is adopt to calculate the viscous airflow field and the four-order Runge-Kutta method is used to solve the droplet trajectory equations. In order to enhance the efficiency of the icing calculations, the multi-block grid technique is integrated into the grid module. Based on the above methods, numerical results in both two cases are presented and the necessary comparisons with the experimental data are given in corresponding chapters. The computational results show that performance of the icing code is very good for the wide range of icing conditions.