This study presents the process of icing analysis to predict the icing shapes and performance of anti/de-icing systems. To predict the particle trajectory and collection efficiency on the 2D airfoil, The trajectory code is developed using the UDS(User Defined Scalar Transport Framework) of FLUENT. Energy balances are performed to predict the surface temperature distribution on the 2D airfoil. A various tests results which contain the ice shapes and temperature distribution are considered to validate the numerical method and results.