The invention relates to an apparatus and a method for replacing and maintaining a cross arm of a distribution wire. According to the technical scheme, the method comprises the following steps: a fixed ring is fixed on a pole; a wire is hooked by a U-shaped hook; the U-shaped hook is stopped in an accurate position through a lifting fixing apparatus; the wire is put on a wire fixing plate through the U-shaped hook, and the wire is fixed by a fixing ring for replacing the cross arm. The apparatus and the method have the beneficial effects that the apparatus is provided with a wire traction apparatus; the U-shaped hook is stopped in the accurate position through the lifting fixing apparatus; the wire is put on the wire fixing plate through the U-shaped hook, and the wire is fixed by the fixing ring for replacing the cross arm; the lifting fixing apparatus is a mechanical transmission lifting mechanism; and due to the reliability of the mechanical transmission, the stop position can be ensured to be accurate, so that the apparatus is time-saving and labor-saving.