AtWNK9 is a member of WNK（With no lysine kinase） family in Arabidopsis, and its function remains unclear. In this study, the protein structure, subcellular localization, promoter elements and expression pattern of AtWNK9 were analyzed by using bioinformatics and biological methods. The results have shown that AtWNK9 is located in the nucleus. It is expressed higher in the root of Arabidopsis, and its transcriptional level is strongly induced by abiotic stress treatments such as ABA, NaCl, glucose, heat and cold. These results indicate that AtWNK9 might be an abiotic stress responsive gene and involves in root development.