In view of the limited blow fill of “the third runway expansion project of Hong Kong International Airport”,which requires the use of machine-made sand for environmental protection construction,the cutter suction dredger “OeanYinghao” is modified adaptively.A sand water mixing device is installed at the front of the bridge to mix the machine-made sand and sea water,and then it is transported to the mud pump through the suction pipe of the cutter suction dredger for long-distance blow fill to realize environmental protection dredging.The sand water mixing device can be extended to the construction projects with high environmental protection requirements for hydraulic reclamation and transportation,and may guide the environmental protection relay transportation at home and abroad.