Abstract: In order to explore the molecular mechanism of tobacco potassium nutrition, tobacco seedlings of K326 were treated with low potassium stress for 0, 6, 12 and 24 h. Gene expression profiles of tobacco seedlings at each time point were analyzed. The results showed that a total of 3790 genes were detected with a change of two folds or more in expression level (p<0.05). GO analysis showed that these differentially expressed genes can be divided into functional classifications including antioxidant activity, stress response, transport activity, development process, catalytic activities, biological regulation, metabolism, etc. Among them, 10 genes, including the nitrate reductase gene NIA2, were involved in nitrogen metabolism, and 44 genes, such as UGP, were involved in the metabolism of carbohydrate and sugar. The results of this study indicate that low potassium stress has a broad impact on gene expression of tobacco, and it may affect the metabolism of carbon and nitrogen in tobacco.