Abstract: Containment vessel of AP1000 is designed to be built by modules. Based on the new lifting method called rigging lifting, further improvement to change the containment vessel from four rings to three rings was proposed, and the best location of lifting lugs was studied. The load ratio of the crane and the safety distance was checked. The proposal to lift the containment vessel by three rings was verified. The new rigging plan can reduce safety risk, and improve the installation quality of the containment vessel. The research of the best location of lifting lugs could be used as the guidance for the containment vessel design and lifting plan improvement.