The invention discloses a crab cleaning machine, which comprises a shell and a transmission mechanism, wherein a water accommodating bucket body is sleeved on the shell to form a bucket body with a cavity structure at the bottom a motor and a speed reducer of the transmission mechanism are arranged in the cavity a rotating shaft at the upper end of the speed reducer penetrates through the center at the bottom of the water accommodating bucket body and is connected with an impeller shaft of an impeller at the bottom of a net bucket body in a spliced manner the impeller shaft is arranged in a through hole in the center of a bearing at the bottom of the net bucket body and is matched with the through hole in a rotatable manner the net bucket body is arranged in the water accommodating bucket body in an extractable manner positioning blocks are arranged on two sides of an opening end of the net bucket body and are clamped into positioning slots in two inner sides of the upper opening edge of the water accommodating bucket body and an ozone generator is arranged in the upper part of the shell. By the crab cleaning machine, the body surface of a crab is flushed by water flow impact wave produced by rotation of the impeller and is subjected to ozone sterilization, so that a plurality of crabs can be cleaned at one time and the crab cleaning machine is high in speed, high in efficiency, labor-saving and practical.