Abstract: The HD-Zip transcription factor family is a kind of special protein in plant, playing crucial roles in plant development processes and abiotic stresses response. The protein family includes a highly conserved homeodomain(HD) and a leucine zipper domain(LZ), forming a special structural model. The HD-Zip transcription factor family, including 63 members, can be classified into 4 subfamilies HD-Zip Ⅰ, HD-Zip Ⅱ, HD-Zip Ⅲ and HD-Zip Ⅳ. RNA-Seq analysis of poplar roots, stems and leaves under salt stress was conducted for the differentially expressed genes in different tissues, and reveal the molecular mechanism of the response to stress environment. Therewere 25 HD-Zip genes down-regulated and 21 HD-Zip genes up-regulated in leaves under salt treatment, 42 genes down-regulated and 11 genes up-regulated in stems, and 26 genes down-regulated and 24 genes up-regulated in roots. According to gene annotations in Arabidopsis thaliana, the functions of HD-Zip transcription factor in poplarwere predicted.The conserved domains, structural characteristics and chemical properties of HD-Zip family members were also studied by bioinformatics, providing reference for gene functions of HD-Zip family in poplar.