Abstract: Insulator icing threatens the safe and reliable operation of power systems. The influence of shed structure on ice shape and amount of insulator icing is mainly explained qualitatively from the experimental point of view, and few numerical simulation studies of ice shape based on the icing growth mechanism are available. Therefore, we used FXBW-35/70 to calculate and analyze the variation law of insulator surface freezing coefficient and convective heat transfer coefficient based on the principles of fluid mechanics and thermodynamics, established a 3-D numerical calculation model of insulator without overflow icing, and verified the model by natural icing experience. The results show that the freezing coefficient decreases with the increase of temperature, water droplet diameter, and liquid water content; the convective heat transfer coefficient increases with the increase of wind speed. The growth direction of insulator non-overflow icing is location-dependent, the rod diameter icing grows mainly along the radial direction, and the shed icing grows in both radial and axial directions. The calculated insulator icing characteristics are within 15% of the experimental errors, which verifies the validity of the model.