Abstract: During the first practice of lifting a 20000 m*3 floating roof tank, because the law of lifting force distribution on the tank wall is not clear, the technique of lifting a tank body and the floating roof separately is adopted in order to minimize the stress of the tank wall. On the basis of the practice, this paper discusses the possibility of integral lifting of a tank with the floating roof hanging over the body, so as to remedy the defect of the technique mentioned above to avoid holing a tank bottom for installing a special device for lifting the floating roof; further more, this paper puts forward a relevant computation method and probes into an optimized design of lifting plan based on the computation result, making ready theoretically for reasonable working-out a perfect program in tank lifting and safe undertaking of floating roof tank lifting in the future.