With the growing demand for land in coastal areas, reclamation is increasingly applied to the engineering practice. As the basic link of reclamation engineering, cofferdam formation directly affects the safe and smooth implementation of subsequent land formation and soft ground improvement. This paper presents the development of reclamation engineering and the structure style and construction technology of cofferdam formation. Based on reclamation projects of Hong Kong-Zhuhai-Macao Bridge-Zhuhai-Macao Port Artificial Island, etc, this paper focuses on key technologies such as riprap cofferdam, sandbag cofferdam, composite sandbag cofferdam, plugin steel cofferdam and intelligent control system of construction on water, which provide valuable reference for the promotion and application of the technology.