Abstract: In this paper,combined with the engineering practice,the design parameters of the vacuum system are discussed,which can be applied to large-scale low-temperature multiple-effect seawater desalination and produce ten-thousand tons fresh water daily.Furthermore,the independent design methods and ways which are based in taking in abroad technology in this field are introduced.The design case and engineering practice for reference are provided for designing vacuum system suitable for large-scale low-temperature multiple-effect seawater desalination system in future.