Abstract: The icing with supercooled large droplet can form the complex ice downstream of the deicing boots. Ice accretion due to the supercooled large droplet may result in extremely severe performance degradation to hazard the flight safety. Research objectives in this paper are to understand the ice accretion effects and reveal the formation mechanism of ice at the supercooled large droplet conditions. A numerical solver is developed to investigate the ice accretion, which include the centered finite volume method for solving the N-S equations to get the air flow field, the Lagrangian method for predicting the flow field of droplets, and a revised Messinger model for simulating the thermodynamic process of icing. Considering the supercooled large droplet conditions, the droplet deformation and breakup using Taylor analogy breakup method are investigated. A splashing model is presented to analyze the splashing phenomenon and the droplet impact. For the supercooled large droplets, the effects of droplet diameter distribution on the movement and impingement process are essential for determining the ice shape. Therefore, the size distribution of droplets needs to be considered during icing simulation. The Langmuir D distribution is studied to get the impact characteristics and icing result of multi-scale distribution of large droplets. Using the above methods, ice accretion and icing effects at the supercooled large droplet conditions over the NACA0012 airfoil are simulated. The calculation results are in good agreement with experimental data, indicating that the methods are feasible and effective.