The invention discloses a label sticking device for a carton sealing machine. The label sticking device comprises a rotating disc assembly which comprises two parallelly arranged rotating discs and a connecting shaft connecting the two rotating discs, the connecting shaft is connected with a first fulcrum bar which is connected with a second fulcrum bar, the second fulcrum bar is connected with a rotating wheel which is connected with a third fulcrum bar, one end of the third fulcrum bar is provided with a box assembly which comprises more than one label box used for storing labels, the label boxes are linearly arranged, the bottom of each label box is shaped like a circular arc, and an opened groove is formed in the middle of the bottom of each label box. When a product packing carton moves on a production line, the product packing carton pushes the rotating disc assembly to move upwards and pushes the box assembly to move downwards, the portion, exposed out of the opened groove, of the label in each label box sticks to adhesive tape, and then the carton sealing machine is used for attaching the labels on the adhesive tape to the product packing carton. The label sticking device for the carton sealing machine effectively solves the problems that due to the fact that the labels are put manually, the labor intensity is large, and the production cost is high.