PURPOSE: To provide a purification method for obtaining high-purity β- chloroethanesulfonic acid sodium salt crystals comparable that obtained from Soxhlet extraction method which has been carried out hitherto from water medium so as to avoid difficulty on operation such as evaporation to dryness without using expensive ethanol.

CONSTITUTION: This method for purifying sodium β-chloroethanesulfonate crystals comprises adding an alkylamine hydrochloride to an aqudous solution of sodium 4-chloroethanesulfonate obtained from the reaction of 1,2- dichloroethane with sodium sulfite or the reaction of vinyl chloride with sodium hydrogensulfite, heating and dissolving the mixture and cooling the aqueous solution to ≤20°C to crystallize and filter 1,2-ethanedisulfonic acid radical, sulfuric acid radical and sulfurous acid radical, evaporating water from the resultant filtrate under reduced pressure to concentrate the filtrate, crystallizing a part of common salt among inorganic salts impurities under high temperature, filtering the deposited common salt at a temperature higher than concentration temperature, cooling the resultant high-temperature filtrate to ordinary temperature to partially crystallize sodium β-chloroethanesulfonate, filtering the crystals and recovering the filtrate to circularly use the filtrate.