Abstract: In order to identify the influence of tobacco chemical composition on sensory evaluation, 68 samples of the upper tobacco leaves were collected in 2012 in Zunyi according to the sampling representative principle.The simple correlation analysis results showed that total sugar, reducing sugar, starch, sugar nicotine ratio, the ratio of potassium to chlorine, Shmuck value and ratio of sugar to nitrogen were significantly positively correlated with sensory quality, and total alkaloid, total nitrogen, chlorine and volatile alkali were significantly negatively correlated with sensory quality.The canonical correlation analysis results showed that the total sugar, reducing sugar, sugar nicotine ratio and ratio of sugar to nitrogen were positively correlated with aroma quality, aftertaste, mixed gas, stimulation and smoking total scores; total alkaloid, total nitrogen and alkali were negatively correlated with aroma quality, aftertaste, mixed gas, stimulation and smoking total scores; potassium and the ratio of potassium to chlorine were positively correlated with aroma and aftertaste, chlorine was negatively correlated with aroma and aftertaste.The path analysis results showed that total sugar, total alkaloid, ratio of sugar to nitrogen and nitrogen alkali ratio had significantly positively direct effect on the aroma quality, aroma quantity and aftertaste; Total nitrogen, sugar nicotine ratio and Shmuck value had negatively direct effect on every smoking index.Therefore, improving the content of Zunyi upper leaves sugar components and reducing the content of nitrogen compounds appropriately can help to improve the sensory quality of tobacco.