Abstract: There existed a close correlation between photosynthetic characters of tobacco and its genotypes.The net photosynthetic rate (Pn) of N.rustica L. 93- 1 was higher than that of flue- cured tobacco and sun- cured tobacco(N. tobacum L. ). There also existed differences among different cultivated varieties of N.tobacum L.. The net photosynthetic rates of leading varieties, i. e. K326 and Yunyan 87 were higher and both were fine parent materials. The correlation analysis of photosynthetic characters among different tobacco genotypes showed that there was a significantly positive correlation between net photosynthetic rate and stomatal conductance,transpiration rate. However, there was a negative correlation between Pn and intercellular concentration of CO₂ .