In recent years, extreme weather has occurred frequently in the world, and the contradiction between medium-voltage lines and wildfires has become more and more serious. In order to study the interaction between medium-voltage lines and wildfires, this paper builds a real fault simulation platform and carries out simulation experiments. The research is carried out from two aspects: the contact discharge between trees and wires to ignite trees to induce wildfires and the impact of smoke and flames caused by wildfires below the lines on the lines. The research results show that there is a high possibility that the medium-voltage line and the tree contact discharge will induce a mountain fire, and the accident must be discovered within at least 40 seconds to effectively prevent the further occurrence of the fire, and the relevant mechanism explanation is put forward. When smoke and flames are emitted from the line, a “particle bridge” will be formed. Under the ionization of gas and inorganic salts, conductive conditions will be formed together to cause discharge or breakdown. The breakdown field strength is about 57kV/m.