Field experiment in drought condition was performed to determine the effects of potassium nutrient regulator on the potassium content, proline, total soluble sugar content in flue-cured tobacco leaves, and the root growth of flue-cured tobacco. Results showed that the potassium content, proline, total soluble sugar content, the fresh mass and volume of roots in treated tobacco were significantly higher than the control plants. It suggested that the regulator could enhance the drought tolerance of flue-cured tobacco plants by increasing the contents of potassium, proline and total soluble sugar.