Abstract: This study selected 10 varieties of cultivated beans, inclucling mung bean, cowpea, kidney bean, adzuki bean and broad bean, black soybean, chickpea, mucuna, fenugreek as matarials.Trypsin inhibitor ( TI) activity, polymorphism and stability of beans were tested.The beans TI activity were 47.4 ¹48.9 TIU/g. Fenugreek and Pinhong05200 had the highest TI activity, which were 148.9, 121.8 TIU/g, respectively.Inhibitor activity staining Gelatin-PAGE showed that beans had 5 ¹3 TI bands.The number and the relative content of subunit of legume TI were determined respectively, and there were many differences of subunit properties in diverse cultivars. Through the treatment of extreme heat, acid, alkali, salt and oscillation, the stability characteristics of trypsin inhibitor were analyzed in the level of subunit aiming at provide preliminary structural data for further research on the mechanism of the stability of the trypsin inhibitor and provide guidance for beans in the food processing and forage breeding.