The invention discloses applications of a Bombyx batryticatus water extract in preparation of anticonvulsant drugs, wherein the Bombyx batryticatus is rigidified for more than 5 days, and the rigidifying time is calculated from silkworm death. According to the present invention, by considering the production cost, the Bombyx batryticatus is preferably rigidized for 5-9 days; the preparation methodof the Bombyx batryticatus water extract comprises: weighing Bombyx batryticatus (powder); adding water according to a material-to-liquid ratio of 1:5-1:10; carrying out heating extraction multiple times, wherein each extraction is performed for more than 1 h; filtering the extraction liquid, and concentrating; and carrying out freeze drying to obtain the Bombyx batryticatus water extract; and itis determined that the important factor affecting the Bombyx batryticatus water extract is the rigidifying time, the Bombyx batryticatus rigidifying time with advantages of good efficacy and good stability is provided, and the basis is provided for the standardized production of the traditional Chinese medicine Bombyx batryticatus.