▎ 摘　　要

NOVELTY - The device has a N processing units connected in series according to the direction of desalination liquid flow, where N is a natural number greater than 1. A processing unit connected in series to front-stage waterway of processing unit is the front-stage processing unit of processing unit for any processing unit. The N processing units connected in series to downstream waterway of the processing unit are the downstream processing units of processing unit. Each processing unit includes a pair of electrodes and a bipolar film (300) between two electrodes constituting the electrode pair. The total amount of ion exchange groups of same type in all bipolar membranes in a processing unit is defined as the effective value of processing unit. The effective value of any one processing unit is not less than the effective value of any subsequent processing unit. The effective value of processing unit is greater than the effective value of a subsequent processing unit. USE - Multi-stage electrodeionization device for water treatment device (claimed). ADVANTAGE - The device has high desalting rate at the front end of the waterway, which integrally improves the desalting rate and water yield, prolongs the service life of the whole machine, reduces the waste of water resource, and reduces the filter core size. The device structure is compact, and is suitable for industrial and household water treatment. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the structure of a bipolar film. Bipolar film (300) Cation exchange membrane (310) Anion exchange membrane (320)