The invention discloses a method used for extracting coarse salt from seawater. The method comprises following steps: 1, concentrated seawater from seawater desalination factories is subjected to electrodialysis in three steps: a first stage electrodialysis membrane stack provided with monovalent selective ion exchange membrane is adopted for treatment so as to obtain a desalted liquid I and a concentrated liquid I, a second stage electrodialysis membrane stack provided with common ion exchange membrane is adopted for treatment of the concentrated liquid I so as to obtain a desalted liquid IIand a concentrated liquid II, and the second stage electrodialysis membrane stack provided with common ion exchange membrane is adopted for treatment of the concentrated liquid II so as to obtain a desalted liquid III and a concentrated liquid III; 2, the concentrated liquid III is subjected to evaporation so as to obtain coarse salt. The method is capable of separating multivalent ions in seawater effectively, increasing the purity of coarse salt, concentrating sodium chloride salt solution, reducing subsequent evaporation labor intensity, producing refined salt high in purity through evaporation, and increasing the whole system water recovery rate.