Abstract: To investigate the effects of potassium-solubilizing bacteria on the physiological characteristics of flue-cured tobacco after drought stress and re-watering, Yunyan 87 was used as the test material. A pot experiment was conducted to analyze the effects of the fermentation broths containing potassium-solubilizing bacteria GUSC5, GUSC13 and GUSC18 on root growth. In addition, the contents of photosynthetic pigments, malondialdehyde and osmotic regulators (proline, soluble sugars and soluble proteins) and activities of antioxidant enzymes were also analyzed, including superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), in leaves of flue-cured tobacco after different durations of drought stress and re-watering. The results showed that all the root irrigation treatments with the prepared fermentation broths promoted root growth of flue-cured tobacco after drought stress and re-watering, enhanced root vigor and photosynthetic pigment content, reduced malondialdehyde content, and increased antioxidant enzyme activity and osmotic regulator contents in tobacco leaves after drought stress. After 15 days of drought stress, root vigor, total root length, total root surface area, root diameter, total root volume, root tip number and chlorophyll a content, chlorophyll b content, carotenoid content, SOD activity, CAT activity, POD activity, proline content, soluble sugar content, soluble protein content and potassium content in the leaves of flue-cured tobacco treated with GUSC13 were significantly (P < 0.05) higher than those of the control. After 72 hours of re-watering, CAT activity and proline content in flue-cured tobacco leaves treated with GUSC13 were significantly lower than those in the control. After 168 hours of re-watering, the malondialdehyde content in flue-cured tobacco leaves treated with GUSC13 was significantly lower than that in the control.