The invention relates to an express box sealing device, and mainly solves the problems that due to heavy workload, low working efficiency and high labor cost of existing manual express box sealing, an express company is required to input lots of labors, and the operating cost is increased. The express box sealing device is characterized in that a bearing block (9) in which a center hole (8) is formed is arranged on the inner wall of a rack (1) corresponding to a second air cylinder (4), a piston rod of the second air cylinder (4) penetrates through the center hole (8), the bearing block (9) is externally provided with a crank arm (11) through a bearing (10), and an output shaft of a reduction gear (18) and the crank arm (11) are in belt driving. The express box sealing device disclosed by the invention is capable of enabling a tape roll to revolve and rotate, the tension of a tape is uniform, the phenomena of tape deflection, packaging box toppling and falling, throwing and bumping and the like cannot happen, the labor intensity of workers is reduced, the working efficiency is increased, and the labor cost is reduced.