The steel pile positioning grab boat,because of its positioning characteristics,such as small occupancy of construction waters,small impact of avoidance and high positioning accuracy,is widely applicable to the construction of the excavation narrow waters and the operation channel widening section.Especially in narrow areas, its positioning advantage is significantly better than that of the traditional anchor cable positioning grab ship.It is difficult to control the construction accuracy of grab dredger.Combined with engineering examples,the problems of ultra-depth,construction safety and construction quality in construction are solved,and the results are satisfactory and can be used as a reference for dredging projects with similar working conditions.