The high-pressure flushing device on the drag head of trailing suction hopper dredger can be used to effectively improve the efficiency of dredging operation.The pipeline design of the high-pressure flushing device is still imperfect,and some structures need to be optimized.We carry out three dimensional modeling,simulation calculation and result analysis of a high-pressure flushing device by using numerical method,find that there is vortex flow near the inlet and outlet of the high-pressure flushing branch pipe in the drag head,and the hydraulic loss is large,which leads to the failure of the ideal outlet total pressure during the construction of the drag head and affects the efficiency.In view of these problems,we improve the flow in the pipe by using gradient pipe and circular chamfer.The results show that after optimization,the resistance loss of the high-pressure flushing pipeline of the drag head is reduced,the jet water speed is higher,the total flow of flushing water is increased by about 3%,the outlet total pressure is increased,and the soil breaking capacity is improved,so as to improve the efficiency of dredging operation.