Abstract: The laws of annual changes on chemical components of flue-cured tobacco with 3 grades (B2F,C3F,X2F) from Fenghuang County in 7 years were studied by the way of variance analysis and regressive analysis in order to explore their stability and variation tendency. The results showed that the stability of potassium and chlorine were worst, while that of total nitrogen was best in different years. The differences of chemical components of flue-cured tobacco among years were significant at 1% level, except that total sugar and reducing sugar of B2F grade. The variation tendency of total sugar and reducing sugar increased, while that total nitrogen, nicotine, potassium and chlorine decreased in different years.