Abstract:The paper deals with Hg,Cd and their interaction on chlorophyll content and antioxidant enzyme systems in leaves of tobacco. The result indicates that, as increasing of the concentration of Hg and/or Cd in soil, content of chlorophyll, chlorophyll a/b values and activity of CAT decreased, the activity of SOD increased first and decreased afterwards and the activity of POD increased. The effects of single Hg and single Cd on chlorophyll content and antioxidant enzymes systems were both more obvious than that of the interaction of Hg and Cd.