Disclosed is a process technology for the complete recycling and enhanced graded separation of salts (Complete Recycle-Enhanced Separation Technology, abbreviated to CREST), wherein the process technology belongs to the fields of the treatment of desulfurization wastewater from thermal power plants and the treatment of industrial wastewater from other industries, and specifically comprises the following steps: 1) the extraction of crystalline magnesium hydroxide; 2) the extraction of calcium sulfate; 3) the enrichment of boron ions; and 4) the purification of a sodium chloride solution. By means of the graded deep salt separation process provided in the present invention, flue gas desulfurization wastewater from thermal power plants is completely recycled for the first time; and after treatment by means of this system, no new wastewater and solid waste are generated, realizing zero discharge and recycling in the true sense, and thus having huge market demand and benefits.