Abstract: Resistant and susceptible varieties of Astragalus adsurgens were treated with exogenous hydrogen peroxide (H₂O₂) or with ascorbic acid (AsA), and after treatment were inoculated with an Embellisia astragali spore suspension. The effect of H₂O₂ treatment on disease resistance of yellow stunt and root rot disease of A. adsurgens was evaluated by recording the incidence of disease, a disease severity index, H₂O₂ concentration, the activities of the enzymes peroxidase (POD), polyphenol oxidase (PPO), β-1,3-glucanase (Glu), chitinase (Cht), catalase (CAT) and superoxide dismutase (SOD). The H₂O₂ contents in inoculated plants were higher than in the uninoculated plants. Also, the maximum observed H₂O₂ contents in resistant were lower (929 μmol/g 38 h after inoculation) than in the susceptible variety (986 μmol/g 24 h after inoculation). The disease infection rates and disease index of both resistant and susceptible varieties were reduced by exogenous H₂O₂ application and increased by AsA application. The activities of the plant enzymes tested were increased to varying degrees by H₂O₂ treatment, and activities in resistant plants increased more than in susceptible plants. The results suggest that exogenous H₂O₂ stimulated the resistance of A. adsurgens to the pathogen and reduced the infection rate by regulating plant enzyme activity.