Abstract: To make clear the factors affecting the browning and the change of chemical components in aged tobacco leaf,the contents of pigments,polyphenol,potassium,chloride,reducing sugar,and starch in and pH value of tobacco leaf during aging were determined,and their relation to browning degree of tobacco leaf was studied.The results of simple correlation,multiple correlation and regression analysis showed that the correlation between browning degree and polyphenol content was extremely significant,however,it diminished gradually with the proceeding of aging.The linear regression relation between browning degree and polyphenol,protein,starch,reducing sugar contents and pH value was significant. It was concluded that the browning of aged leaf was influenced by many chemical components,particularly polyphenol.