During the construction process of the automated phaseⅠcontainer terminal renovation project in Luojing port area of Shanghai Port,it is necessary to cut off the pile foundation below the old dock along the design elevation,and on the basis of retaining the underwater residual piles,new pile foundations should be installed in the gaps between the residual piles.In response to the high safety risks of pile cutting and underwater collision during the construction process,multiple process comparisons,research,and practical comparisons are conducted.Finally,the method of divers cooperating with pile cutters is adopted to dismantle old pile foundations,reducing the safety risks of divers working underwater for a long time.New technologies such as “laser radar scanning+3D modeling” are also reasonably used to conduct semi visual prediction of pile positions and guide the adjustment of the entire pile foundation construction process.At the same time,combined with the vibration pile driving construction technology,the collision problem between new and old pile foundations is reasonably and effectively avoided,and the overall deviation qualification rate of the engineering pile foundation construction reaches over 95%.The research results can provide a reference for the upgrading and renovation of similar old docks.