Abstract: For further understanding the structure and function of CuZnSOD gene in Nicotiana tabacum, the full-length sequence of CuZnSOD gene encoding zone was successfully amplified from young leaves of 13 tobacco cultivars and Nicotiana sylvestris, and its sequence was analyzed. It was revealed that the CDS contained 291 base pairs and encoded a protein of 96 amino acids. The results of key nucleotide sequence comparison showed that the similarity of CuZnSOD genes with other plant species in Genbank was up to 94%. Meanwhile, the analysis of phylogenic tree based on CuZnSOD CDS of tobacco indicated its closest genetic relationship with tomato and potato. The results of quantitative PCR analysis of the expression levels of CuZnSOD showed significant differences in expression pattern between low-temperature and weak-light exposure samples of 13 cultivars and Nicotiana sylvestris. The expression pattern analysis of CuZnSOD gene in tobacco would provide clues to the revelation of the adaptation mechanism of tobacco to environment, as well as the physiological mechanism of anti-oxidation.