The layout of the second-line ship-lock always needs adjustment because of the existing buildings,land resources,etc.Based on the Dongdaying Port ship-lock engineering,we study the surrounding environment conditions,construction conditions,environmental protection requirements,and utilization conditions,point out the shortage of the original design,and put forward the optimization approaches including the use of the high pile cap forked revetment structure in outer river approach channel,high pile abutment separates diversion dike structure in the outer river diversion dike,the SWM method in the lock chamber construction foundation pit,etc.,by which,we solve the technical problems of building second-line ship-lock under the condition of limited space,shortage of resources and strict requirement of environmental protection.