In order to meet the construction requirements of cutter suction dredger in the wind and waves,this paper makes an in-depth study on the three cable positioning control system,develops a set of automatic three cable positioning system suitable for cutter suction dredger,and successfully applies the system to Tianqi dredger.By using double PID control idea,the system can effectively control the speed loop of the frequency converter,which can not only ensure the ship to walk in the direction of the construction line in the step process,but also reduce the impact of the wind and waves on the positioning process,so as to realize the rapid positioning of the ship and improve the construction efficiency.