MYB transcription factor is one of the most representative transcription factor families in all eukaryotes. It is widely involved in plant development, phenylpropanoid metabolism, biotic and abiotic stress response, hormone response, and cell morphogenesis. In this study, StMYB44 gene (GenBank accession number is XM_006367359.2) was cloned from potato ‘Qingshu 9’, whose sequence length was 963 bp, encoded 320 amino acids that contained two SANT domains. The result of quantitative realtime PCR showed that StMYB44 had the highest expression in flowers and the lowest expression in stolon; StMYB44 was upregulated under sucrosefree treatment and downregulated under highconcentration sucrose treatment (6%, 9%). Construction of expression vector and genetic transformation of tobacco found that the growth of StMYB44 mutant under sucrosefree conditions was significantly better than that of wildtype, while at high sucrose concentration (6%, 9%), the growth of StMYB44 mutant was weaker than wildtype, and the higher the sucrose concentration, the difference is greater. These results indicates that sucrose concentration can regulate the expression of StMYB44, suggesting that this gene may play an important role in plant response to sucrose.