Six maize（Zea mays L.） varieties with different resistance to maize rough dwarf virus（MRDV） wereused to analyze POD activity and isozyme pattern of healthy and diseased leaves in the tasseling stage. The resultsindicated that POD activity appeared susceptible varieties ＞ moderate resistant varieties ＞ resistant varieties. PODactivity increased after the plants were infected by MRDV and the increasing extent showed resistant varieties ＞moderate resistant varieties ＞ susceptible varieties. So, the stronger resistance, the less POD activity, and the greaterincrease of POD activity. POD isozyme was different in resistant and susceptible varieties. The band of Rf 0.93 wasrelated to the resistance to MRDV. The increasing extent of Rf 0.28 expression after MRDV infection was related tothe inductive resistance. Therefore, the stronger resistance, the greater Rf 0.93 expression, the greater increasing ex-tent of Rf 0.28 expression after MRDV infection.