Abstract: To improve the over-winter ratio of Hemarthia compressa in high altitude areas of Chongqing, cuttings of Hemarthia compressa were irrigated by different concentrations of CaCl2 solution before cold stress. The changes of activities of antioxidant enzymes (SOD, POD, and CAT) of leaves at 4 ℃ were determined. Evidences showed that changes of SOD activities increased first and then decreased, then increased again. But treatment of 1-4 SOD activity is always decreased, treatment of 2-2 and 2-4 is first increased and then decreased, 2-3 is first decreased and then increased. POD activity was first increased, then decreased, and then increased. After 72h under cold stress, POD activities of treatment 1-3 and 2-3 were the highest in two materials, respectively 652.65 U/g, 708.10U/g. The change of CAT activities was decreased dramatically, after 72h under low temperature stress, treatment of 1-3 and 2-2 CAT activities in leaves is highest, respectively 21.68U/g, 17.28U/g.Ca2 at 10 mmol/L could significantly increase SOD, POD and CAT activities in the later stages. Ca2 has a protective effect to membrane structure under cold stress, could improve the cold resistance.