A dredging project in Iraq uses large cutter suction dredger to construct foundation trench slope,and the construction period is only three months.To solve the problem that the slope accuracy is high and the cohesive soil is not easy to collapse into slope,we decide to study the high-precision one-time forming technology of large cutter suction dredger for foundation trench cohesive soil slope.By correcting the transverse speed of the cutter and the lifting speed of the cutter,the matching control of the transverse speed of the cutter and the speed of the bridge frame is realized.By carrying out typical construction and a large number of field experiments,the optimal cutter traverse speed of four construction methods under different excavation depths is determined,which includes uphill normal cutter excavation,uphill reverse cutter excavation,downhill reverse cutter excavation and downhill normal cutter excavation,and the quality of the slope is guaranteed.The results show that this technology can meet the requirements of high precision and short construction period,and reduce the production cost.The average super width is reduced from 2.0 m to about 0.5 m,and the slope repair effect is remarkable.