The present disclosure relates to a method for extracting chitin nanocrystals through electron beam irradiation comprising the steps of: (i) irradiating a chitin-based solid material with an electron beam; (ii) washing the chitin-based solid material subjected to electron beam irradiation; (iii) adding a basic solution to the washed chitin-based solid material; (iv) high-pressure homogenizing the chitin-based solid material dispersed in an aqueous system to which the basic solution is added, to prepare a suspension containing chitin nanocrystals.