Characteristics of chemical components of flue-tobacco leaves were studied by detecting total sugar，reducing sugar，nicotine，total nitrogen，potassium and chlorine of 54 samples with 3 grades(B2F，C3F，X2F) from the typical tobacco-growing towns of Shaoyang City，and its usability was evaluated by using fuzzy mathematics. The results showed that： (1)The average concentration of total sugar，reducing sugar，nicotine，total nitrogen，potassium，chlorine were at right levels，and its coordination was good. (2) The concentration difference of chemical components in differently graded tobacco samples was significant，but that between tobacco-growing counties and between tobacco-growing town were not statistically significant．(3)The usability index of chemical components in different grades was：C3F＞B2F＞X2F. (4) The usability index of chemical components in Shaoyan county was highest，and that in Longhui county was lowest. (5) The usability index of chemical components in different towns at B2F grade was as follows：Matouqiao＞Hebai＞Xiatangyun＞Liuduchai＞Zhouwang＞Fengtian，at grade C3F，it was as follows：Xiatangyun＞Hebai＞Zhouwang＞Fengtian＞Matouqiao＞Liuduchai，at grade X2F，it was as follows：Fengtian＞Hebai＞Matouqiao＞Liuduchai＞Zhouwang＞Xiatangyun.