In the dam flood discharge area,the lock cofferdam construction faces problems of large flood discharge flow and large height of water,which demands high technical performances,such as anti-scouring stability,anti-leakage of cofferdam,etc.Therefore,it is necessary to grasp the key points of design and construction of the cofferdam.This paper focuses on the successful experience of the design and construction of the cofferdam of Fuchun river lock expansion project.