The invention discloses an automatic box sealing machine. A box sealing mechanism, a box body guide mechanism, a top pressing mechanism, a sensor and a control system are arranged on a rack, so that an integral automatic box sealing machine is formed. The box sealing mechanism mainly comprises an adhesive tape feeding and sticking device, an adhesive tape is provided by virtue of an adhesive tape bearing roller and a guide roller, a part of adhesive tape is rolled onto the front surface of a box body by a pressing and sticking roller, the other part of the adhesive tape is brushed onto the upper surface of the box body by a hair brush, and the stuck adhesive tape is cut off by a cutter; the top pressing mechanism is used for fixing a to-be-sealed box body on a working platform, and reliable support force is provided for the sealing of the box body with the adhesive tape; and the height of a bearing bridge on a mechanism support frame and the distance between two guide tapes of the box body guide mechanism are adjusted, so that the box sealing requirements of different types of box bodies can be satisfied. The automatic box sealing machine has the advantages of stability and reliability in operation, reasonable design, simple structure, low cost and long service life.