Desalination of seawater by electrodialysis is achieved through an electrodialysis desalinator. The desalination principle of the desalinator is that under the action of an external DC electric field, when the salty raw water flows through the compartment composed of anion and cation exchange membranes and partitions, the anions and cations in the water begin to move in a directional manner, the anions migrate toward the anode, and the cations toward the anode. Cathode direction migration. Since the ion exchange membrane has selective permeability, the fixed exchange groups of the cation exchange membrane (referred to as the cation membrane) are negatively charged, thus allowing the cations in the water to pass but blocking the anions. The fixed exchange group of the anion exchange membrane (abbreviated as anion membrane) is positively charged, so it allows anions in the water to pass and blocks cations, causing the ions in the fresh water compartment to migrate to the concentrated water compartment, thereby achieving the purpose of desalination.