The deep silt sand soil was encoutered in constructing temporary cofferdam for Zhangjian Reservoir Reinforcement Project.The design and construction of the cofferdam cannot fully meet the requirements of specification.By scheme comparison,the extrusion method is adopted to construct tempory cofferdam.It has the characteristics such as fast construction progress and safety operation.It meet the requirement of time limit for the project and reduce construction cost.It can be referred for similar projects.