Abstract: To investigate water retention effects and physiological regulation mechanism of water retaining agents on the growth and development of different flue-cured tobacco varieties, a pot experiment was conducted to study the effects of different water retaining agents on the agronomic traits, root vigor, antioxidant enzyme activity in leaves, malondialdehyde (MDA) content and proline content of two flue-cured tobacco varieties (Yuyan 6 with strong drought resistance and Yuyan 10 with weak drought resistance) under moderate drought conditions. The results showed that:1) The application of water retaining agents increased plant height, stalk circumference, leaf number and maximum leaf area of the flue-cured tobacco, and promoted the root vigor of tobacco; especially for Yuyan 10. 2) Water retaining agents decreased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in the flue-cured tobacco, however their effects on the two varieties differed. 3) Water retaining agents reduced the MDA content in the flue-cured tobacco, especially in Yuyan 10. 4) Water retaining agents reduced the proline content in the flue-cured tobacco under drought condition, and the proline content decreased more obviously in Yuyan 6 than in Yuyan 10. Therefore, the application of water retaining agent promoted the adaptability of Yuyan 10 to drought stress. The regulation ability of water retaining agent B (polymer absorbent material containing potassium, prepared by using modified starch, acrylonitrile and acrylamide as raw materials) on the growth and physiological metabolism of the flue-cured tobacco was better than that of water retaining agent A (sodium polyacrylate).