CDPKs(calciumdependent protein kinases) are important calcium signal receptors and response proteins, which play important roles in response to various abiotic stresses in plants, such as drought, low temperature and salinity. To study the effect of cotton GhCDPK1 gene to drought stress, this study used quantitative realtime PCR to analyze the gene expression under PEG stress. The results showed that GhCDPK1 gene was upregulated by drought stress. Moreover, plant expression vector was constructed and GhCDPK1 gene was introduced into tobacco by Agrobacturiummediated leaf disk transformation method to identify the gene function. The results showed that after drought stress, the water retention capacity of transgenic plants was significantly higher than that of wild type plants; the contents of chlorophyll, proline, soluble protein and the activities of POD and SOD in transgenic tobacco plants were higher than that of wild type, whereas the content of MDA was lower than that of wild type plants. These results indicate that GhCDPK1 gene, as a positive regulator, was induced by drought stress, and overexpression of GhCDPK1 gene can enhance the ability of plants to resist drought stress by accumulating more osmotic adjustment substances, enhancing the activity of the antioxidant system and maintaining the stability of the cell membrane.