Abstract: The plant cell wall fundamentally determines plant growth. Furthermore, UDPG is the essential precursor for cell wall biosynthesis in plant, and it is demonstrated that the pool of UDPG is mainly derived from Glu−1−P and UTP by UGPase and USPase. In this study, the PyUGPase−A, PyUGPase−B and PyUSPase of Populus yunnanensis encoding proteins were predicted and analyzed by bioinformatics tools and URL. Meanwhile, one-year-old upright and inverted cuttings of Populus yunnanensis were used as materials, and theirmain branch length and diameter were measured, the analysis on the three genes expression in stem tips, tender leaves, mature leaves, stems and roots of upright and inverted cuttings of P. yunnanensis were carried out by RT−qPCR technology. The aim was to explore the tissue specific expression patterns of the 3 genes, and provided a preliminary research basis for revealing the mechanism of the 3 genes regulating cell wall synthesis and deeply regulating the growth of P. yunnanensis. The results showed that the full length and encoded amino acids of PyUGPase−A, PyUGPase−B and PyUSPase genes were 1410 bp and 469 amino acids, 1410 bp and 469 amino acids, 1875 bp and 624 amino acids, respectively. All the 3 proteins did not exist in the peptide and transmembrane domain, and they were all positioned within the cytoplasm of a hydrophilic protease. Homology comparison analysis showed that the amino acid encoded by PyUGPase and PyUSPase genes were highly homologous(>85%) with those encoded by UGPase and USPase genes in other species. The main branch length and diameter of inverted cuttings were lower than those of upright cuttings, but the differences were not significant. The expression of PyUGPase−A and PyUGPase−B genes were relatively high in the mature leaves of the 2 types of cuttings, and up-regulated in the tender leaves of inverted cuttings. However, PyUSPase gene was down-regulated in the 5 tissues and highly expressed in roots.