The invention discloses an electric wire post welding device and a working method thereof. The electric wire post welding device comprises an electric wire post clamp plate provided with two semicircular cavities. The circular arc diameter of the electric wire post clamp plate is matched with the outer diameter of a reinforced electric wire post. The electric wire post welding device further comprises electric wire post support seats, a levelness measurement device, an electric wire post tension device and an electric conduction sliding ring. Each electric wire post support seat comprises a bottom layer support, a middle layer support and an upper layer support which are connected movably from bottom to top. A speed reducing motor and an electric welding machine lead support seat are installed on support wheels of one electric wire post support seat. According to the electric wire post tension device, two clamping stirrups pull close two segments of electric wire posts through tension screws. According to the electric wire post welding device and the working method thereof, the production cost can be reduced. Through usage of an electric driving device and the electric conduction sliding ring, the automation degree is improved. The levelness, the height and the concentricity of the butt welded electric wire posts can be adjusted through the electric wire post support seats, so that the welding quality of the butt welded electric wire posts can be ensured, and safety accidents are prevented.