Zhejiang petrochemical 40 million tons of refining and chemical engineering integration project is assorted with 7¡Á15000 tons/day of low temperature multi-effect seawater desalination project,in which the engineering and procurement is contracted by Shanghai electric. As the model demonstration in Chinese petrochemical industry, the project not only contains the largest capacity of seawater desalination, but also can be supplied with hot water as the heating resource. The seawater desalination system is designed to meet the request of various operating condition by switching operating mode between MED-TVC and F-MED.