Steel cofferdam riverbed bottom cleaning device

A steel cofferdam riverbed bottom cleaning device comprises a sand suction pipe which is provided with a lifting ring and is lifted through a lifting appliance, one end of the sand suction pipe is a suction inlet and extends into a steel cofferdam to be opposite to silt, the middle section of the sand suction pipe crosses the top of the steel cofferdam, and the other end of the sand suction pipe extends out of the steel cofferdam to discharge the silt. A breather pipe is connected to the position, adjacent to the suction inlet, of the end of the inner side of the sand suction pipe, one end of the breather pipe penetrates through the sand suction pipe, the open end of the breather pipe is opposite to the riverbed, the other end of the breather pipe is connected with a high-pressure machine, river water in the sand suction pipe is driven by high-pressure air to flow and form negative pressure, suction force is formed at the suction inlet, and silt is sucked and discharged out of the steel cofferdam. The steel c