Aiming at the problem of difficulty in the condition without the cover of large cylinder shell structure construction,this paper discusses the design characteristics such as large diameter,the innovative use of exchange filling,the structure of the need for a hundred years of anti-corrosion,using a variety of methods for the stability calculation,etc.It also discusses the difficulties of construction such as strong winds and big waves in the construction site,strict precision request of measure and orientation,using the 12 hammer linkage for the first time,etc.Then it summarizes the control points of large cylinder shell structure construction such as high quality for the cylinder shell structure welding,the heavy anti-corrosion coating and the supervision in the whole process,the high precision of underwater trench excavation,appropriate construction space,and the prototype observation to the cylinder.