Abstract: Experiments were carried out to analyze the composition and content of alkaloid in burley tobacco of Binchuan and different varieties from different areas in Yunnan, and the proportion of converters and nicotine conversion rate were calculated to determine the characteristics of alkaloid composition and the feasibility of variety improvement. The results showed that the average content of alkaloid in Binchuan burley tobacco was 3.31%, which was similar to that in imported quality burley tobacco, nicotine conversion was not a problem of imminent concern, though the variation of nornicotine content and nicotine conversion rate was found at different experiment points. Comparison of conversion rate for individual plant between different burley varieties showed that OD911 and YNBS1 with lower average conversion rate had relatively less problem of nicotine conversion; most plants of TN86 were low converters; the average conversion rate of TN90 was 11.84%, there were some plants with high conversion rate of 10%; Eyan 1 had a higher proportion of converters, about 16.67% of plants were high converters, and the average conversion rate reached 30.51%, thus the systemic selection and variety improvement were necessary.