Seven foxtail millet varieties were studied for activities of superoxide dismutase (SOD),peroxidase (POX) and polyphenol oxidase (PPO) in different periods. The results showed that after foxtail millet were infected with head smut, three enzymes activities all increased significantly. Enzyme activities of resistance varieties were stronger than that of susceptible varieties. Changes of activities of protective enzymes were able to play an important role in resistance to head smut in foxtail millet.