The major part of Wanhe guide and drainage canal of Shihutang navigation-power project is at the old channel of Ganjiang River.Owing to the complex geological conditions and high underground water level,the conventinal mechanical excavation method is diffcult to adopt.In dredgin construction,using cutter-suction dredger is not only faster,but also can avoid the investment.The superiority of cutter-suction dredger construction is fully embodied under special conditions.