Abstract: The leaf senescence and active oxygen metabolism of different-type wheats under drought were studied.The results indicate that leaf senescence is associated with the decreases of SOD，POD and CAT activities.A marked increase of MDA content and a product of lipid peroxidation are observed during leaf senescence.Cold type wheat has a canopy temperature continuously lower than that of control，especially during the milk-filling period.Many of its characters，such as chlorophyll content，soluble protein content and active oxygen（SOD，CAT，POD）are more superior than those of warm type wheat.Active oxygen metabolism may be responsible for the relationship between canopy temperature and grain yield.