A blade mounting bracket includes a blade mounting part and a handle connecting part. A blade mounted on the blade mounting bracket defines a strip-shaped hole. The strip-shaped hole includes a mounting section and a tightening section. A width of the mounting section is greater than a width of the tightening section. The blade mounting part includes a base and a fixing piece connected with the base. An upper surface of the fixing piece is matched with the mounting section. An upper portion of the fixing piece extends downwards to connect with the base. Grooves are formed between the upper surface of the fixing piece and the base. The fixing piece includes a fixing block matched with the mounting section. The grooves and the fixing block fix the blade in a plane in which the blade is located.