Abstract: Wind turbines often suffer from disasters such as lightning strikes and ice coating, significantly impacting the normal operation of the turbines. The installation of electrothermal ice-melting devices on the blades can effectively remove ice from the blades, but the impact on the lightning strike probability on the blades and the reliability of the original lightning protection configuration (receptors and down conductors) is not yet clear. To investigate the mechanism of the effect of ice-melting devices on the lightning attachment characteristics of the blades, a 1:30 reduced-scale rotatable 3 MW ice-melting wind turbine blade was designed for long-gap lightning discharge experiments. The experimental results indicate that when the lightning leader develops on the windward side of the blade, the ice-melting blade is more prone to have the phenomena of lightning receptor failure, and lightning strike at the junction of the ice-melting device and the blade body. In the most severe case, the protection efficiency of the lightning receptor is only 55%. A model of the electric field distribution on the ice-melting blade was established, revealing that the ice-melting device alters the original electric field distribution on the blade surface, causing distortion of the electric field at the junction of the ice-melting device and the blade body, making it more prone to corona discharge. Simultaneously, the rotation of the blade causes the surrounding positive charges to distribute in an arc shape, accelerating the formation of stable leader above the ice-melting device, making it more susceptible to lightning strikes. Therefore, enhanced lightning protection measures are recommended for the ice-melting device location. The obtained results provide reference for the in-depth integration of lightning protection and ice-melting protection for turbine blades.