The wharf dredging is a very special kind of dredging project, especially under the high-piled wharf. The difference of water depth under the wharf and at wharf apron of Jintang Dapukou container dock is now above 10 m. It is known through measurement that the siltation under the pier is over 10 m, which seriously affects the safety of the pile group. Therefore it is urgent to find a kind of device to clear away the silt under the pier. In view of the situation that this device is uncommon in China at present and expensive to import from abroad, the lab carries out an experiment at the wharf apron with the self-developed device deep-suction I to provide technical support for the dredging engineering under the pier.