Abstract: In order to explain the physiology mechanism of appropriate potassium application on improvement of self-defensive capabilities and enhancement of disease resistance, 3 different doses of potassium nutrition were applied to flowering cabbage seedlings inoculated with anthracnose pathogen, then the activities of superoxide dismutase(SOD), peroxidase(POD), catalase(CAT), and content of malondialdehyde(MDA) were detected. The results showed that the anthracnose pathogen significantly affected the activities of SOD, POD, CAT and content of MDA in flowering cabbage. The activities of SOD, POD, and CAT decreased at the early stages of disease infection and increased at the late stages, while the content of MDA was increasing slowly. The results also showed that potassium nutrition had an effect on the induction of anthracnose pathogen to the cell membrane protective enzyme system in flowering cabbage. The appropriate potassium nutrition enhanced the effect of anthracnose pathogen treatment of SOD and CAT activities and inhibited the effect on the activity of POD and MDA content. Therefore, appropriate potassium application to the seedlings inoculated by C. higginsianum could validly regulate metabolic balance system of activated oxygen species (AOS) and finally improve the disease resistance of seedlings.