Underwater dredging construction under confined space conditions has a high requirement for equipment and technology，and a great impact on the overall construction schedule and cost of the project. Taking a wharf project as an example，this study optimizes the overall construction organization of the wharf，adopts the technology of sinking piles first and then dredging，and conducts combined construction with a small excavator，a modified cutter suction dredger，and underwater intelligent dredging equipment. The aim is to systematically solve the problem of underwater dredging under confined space conditions and thereby reduce the construction period of the project. Resorting to the section method and a two-dimensional tidal-current sediment mathematical model，this paper puts forward construction quality assurance measures for dredging soil between piles of a high-piled wharf and conducts a quick evaluation of the states of soil dredging between piles and mud dumping. The following observations can be made from the results：1）The quick evaluation method for dredging volumes can effectively deal with the problems of over-excavation and under-excavation in the confined space. 2）The influence of sediment siltation in the wharf area can be reduced by setting the mud dumping point 35 m away from the wharf front on the sea side.