The invention discloses an automatic carton box labeling machine which comprises a base, a workbench, a controller, a label printing and cutting module, an electric cylinder, a label adsorption block and a water passing device, wherein based on a labeling direction, the workbench is fixed to the base; the controller is mounted on the rear side wall of the workbench; the label printing and cutting module is mounted on the workbench; the label printing and cutting module is used for printing and cutting bottomless paper labels; a positioning block is fixed on the workbench; the positioning block is positioned at one side of a label outlet of the label printing and cutting module; the electric cylinder is horizontally fixed on the positioning block; a supporting rod is horizontally arranged in the positioning block in a telescopic penetration mode; the supporting rod is positioned below the electric cylinder; the middle upper end part of the label adsorption block is fixedly connected to a telescopic pole of the electric cylinder; the middle lower end part of the label adsorption block is fixedly connected to the supporting rod; and the water passing device is rotatably positioned on the workbench and is positioned in front of the label adsorption block. The automatic carton box labeling machine can improve the labeling efficiency and can reduce the cost.