Abstract: Owing to the strong permeability of the cofferdam foundation in the expansion and modification project of the Qinhuai River shiplock， the cofferdam foundation must have a good anti-seepage capacity to ensure that the main body of the shiplock is under construction on a dry site. There were some problems in the original design proposals for the cofferdam structure， and hence it is necessary to further optimize the design schemes. After making the comparison and optimization of three kinds of the cofferdam structure design schemes:“filling sand bags + impervious curtain, clay filling + impervious curtain + backpressure platforms and clay filling + impervious curtain + steel sheet pile”, a final design scheme “clay filling + impervious curtain + backpressure platforms” has been adopted, thus ensuring the safety of the cofferdam structure and flood control progress, and having significant economic benefits. All of those may provide a useful reference for the design of the cofferdam structure with similar geological conditions.