Plant can produce reactive oxygen species (ROS) in normal physiological activity. However, ROS can increase dramatically by environmental stress. The increase may break the ROS balance in the plant. To control ROS levels in plants, an antioxidant system is needed to protect the cell. This paper introduced the types and functions of antioxidant enzymes, and studied the effects of plant and environmental factors on the activities of antioxidant enzymes. At last, the paper discussed the research hot fields of the effect of environmental stress on antioxidant enzymes, and gave the research strategies to the problems which happened in the studies.