Abstract: Deep offshore engineering projects such as TLP, SPAR, semi-submersible drilling platform and etc. have floating body, and require high accuracy for center of buoyancy. Construction precision control of floating body is the important measure for ensure accuracy for center of buoyancy relative to traditional jacket offshore structures. So how to control, when to control and using which tolls to control construction precision are the most critical for floating construction. This paper introduces normal control measure for construction precision control and detail describes one control principle of precision control system. Performing this precision control system can ensure the high requirement of center of buoyancy and improve efficiency and economic benefits.