The invention relates to the technical field of mechanical treatment, in particular to a metal tube grinding device, which comprises a box body, wherein a through hole for allowing the metal tube to penetrate through is formed in the box body; a grinding device is mounted inside the box body, and comprises four abrasive cloth wheels, four rotating shafts, eight gears, eight driving belts and a motor; the abrasive cloth wheels are connected with the rotating shafts; two gears parallel to the abrasive cloth wheels are mounted on each rotating shaft; the gears are connected through the driving belts; one of the gears is connected with the motor. The metal tube grinding device is simple in structure and convenient to operate due to the facts that manual operation of rotating the metal tube is avoided, and the metal tube can be well grinded within an area surrounded by the four abrasive cloth wheels; as the abrasive cloth wheels are uniform in wear and tear when working, the metal tube grinding device is longer in service life.