Mixed-bed exchanger, also known as mixed bed, refers to a system where water first passes through a cation bed of hydrogen form cation exchange resins, and then an anion bed of anion exchange resins in hydroxylic form. The hydrogen form cation bed is used to remove cations from the water; and the hydroxylic form anion bed is used to remove anions from the water. Mineral salts can be generally removed from the water via the mixed-bed exchanger. To achieve better desalination effect, cation bed usually contains strong acid cation exchange resins; and anion bed usually contains strong base anion exchange resins. Besides, mixed bed can also be divided into internal regeneration mixed bed and external regeneration mixed bed.