The supercooled large droplet(SLD) icing detection is a hot spot in the field of aircraft icing detection and protection. Through the analysis of the characteristics of large inertia, high temperature and backward flow of SLD, the backflow characteristics detection method of SLD icing is proposed. The finite volume method was used to study the water trajectory, impact characteristics and icing dynamic characteristics of the water droplets, and the icing mechanism was simulated and validated. In order to solve the problem of freezing coefficient, two ice detector configurations are proposed and numerical simulation is carried out. The result shows that there is a big difference between the small water droplet and the SLD in the icing region of the detector. The icing of the SLD can be identified by detecting the icing region on the probe, and this configuration can solve the freezing coefficient problem to a certain extent.