Mustardase and glucosinolate are stored in different cells. When attacked by diseases and insects, the substrate and the enzyme meet, and the glucosinolate is reduced to a toxic compound for defense. The research progress of plant mustard enzyme defense system is reviewed, including the structure of gene family, gene expression regulation, cell positioning of mustard enzyme, mustard enzyme of other organisms outside the plant, origin and evolution of glucosinolate/ mustard enzyme system and its possible Functions etc. When the mustard plant tissue is damaged, the glucosinolate directly contacts with the myrosinase, and hydrolyzes the glucosinolate to isothiocyanate, nitrile and other toxic substances to protect itself from further damage by herbivores.