Abstract: It is an important way that transcription factors regulate the expression of target genes at the transcriptional level，to regulate plant growth and development. In this study，we cloned the full-length cDNA of PtoMYB057 transcription factor in poplar. The results of fluorescent quantitative PCR showed that the transcript of PtoMYB057 was the most abounded in xylem. Phylogenetic analysis showed that PtoMYB057 had higher similarity with Arabidopsis MYB006，MYB008，MYB003，MYB007，MYB108. Subcellular localization showed that PtoMYB057 was localized in nucleus. Overexpression of PtoMYB057 in transgenic tobacco indicated that this gene played important roles in plant growth and development.