In view of the problems such as drag teeth is hard into the soil,drag head is blockage and shutdown when the large trailing suction excavate stiff clay,we adopt special high-pressure flushing system（maximum pressure 38 MPa）,add three high-pressure flushing auxiliary device,and design the suitable injectors in the drag head based on the original drag head model of the large trailing suction hopper dredger.The drag head for high efficiency excavating clay has been successfully developed,which effectively solves the problem of drag head blockage and shutdown,and raises the efficiency of trailing suction hopper dredger construction.It can provide the reference for similar problems.