Cities are overwhelmed because of the rising sea-level and the explosive growth of population,living place of human beings is scarce increasingly.Under the circumstances,some designers turn to the possibility of floating structure.Firstly,the article discusses the design methods of the floating city based on the constructive practice of the floating unit that the author did in Paris with Bellastock team.As architects,we need to introspect from the point of energy,resource,culture,architecture design and the urban design,as a consequence for us to explore the new residence mode for human beings in the future.