The invention discloses a cross-arm bracket and a method for replacing a cross arm through employing the same. The cross arm bracket comprises two square steel tubes, and the square steel tubes are provided with a leaning frame. The inner side of each square steel tube is provided with a left jacking frame and a right jacking frame, and corresponding ends of the two square steel tubes are hinged to an upper connection plate and a lower connection plate, which are arranged in a staggered manner, and are provided with a plurality of connection position adjustment holes. The interiors of upper and lower adjustment holes are provided with connection bolts and nuts, and the other sides of the two square steel tubes are provided with screws. The rear ends of the screws are hinged to the rear square steel tube, and one end, corresponding to the screws, of the front square steel tube is provided with gaps. The front parts of the screws are inserted into the gaps, are provided with threads, and are provided with locking nuts through the threads. The distance between the two square steel tubes, corresponding to the end, is adjusted through the locking nuts. The bracket is simple in structure, is convenient to disassemble, is high in work efficiency, is low in labor intensity, is high in safety factor, and can be operated by one person on a rod.