In order to reveal the function and stress response of CkPHB, we obtained a member of the leucine zipper protein transcription factor (HDZIP Ⅲ) family in Caragana korshinskii, CkPHB gene sequence by designing primer cloning according to transcriptome sequence, and carried out a series of bioinformatics analysis. The tissue localization of CkPHB protein in C. korshinskii leaves was observed by immunohistochemical staining. At the same time, the cloned CkPHB gene was transformed into Arabidopsis thaliana by Agrobacterium tumefaciensmediated method, and the positive overexpression plants were screened for functional verification. The results showed that: (1) the CkPHB gene, a member of the HDZIP Ⅲ family in C. korshinskii was successfully cloned. Its fulllength sequence is composed of 389 amino acids with a molecular weight of 42.83 kD. The protein encoded by CkPHB is hydrophobic and its secondary structure is mainly composed of αhelix. (2) Immunohistochemical analysis showed that CkPHB protein was localized in the xylem region of the vascular bundle of C. korshinskii leaves. (3) Through genetic transformation screening and identification, we finally obtained three T₃ generation plants of C. korshinskii CkPHB gene overexpression line in A. thaliana (CkPHBOE). Compared with wildtype A. thaliana (WT), the CkPHBOE strain of A. thaliana has more developed veins, larger vascular bundle volume and more xylem vessels. The realtime quantitative PCR analysis showed that five genes related to xylem development in CkPHBOE strain (XCP2, CesA7, CesA8, PAL4, F5H) were upregulated compared with WT. (4) The results of drought resistance experiments showed that the survival rate of CkPHBOE strain in A. thaliana was significantly improved under drought conditions. The physiological indexes further supported the above results, indicating that CkPHB overexpression significantly enhanced the drought resistance of transgenic A. thaliana. The research shows that A. thaliana overexpressing C. korshinskii CkPHB gene is more developed and its physiological indexes of resistance are significantly improved, thus enhancing drought resistance, which proves that CkPHB gene plays an important role in promoting leaf vein development and improving plant drought resistance. The results of this study laid a foundation for further studying the drought response mechanism of CkPHB gene in C. korshinskii.