Abstract: Grey incidence analysis is an analytical tool based on grey theory. The basic ideology is to estimate the relation of factors studied by the change of their similarity. According to this theory, through the relation index (k) and relation R, to study the degree of incidence, we analyzed the incidence between the integral rating and the inner quality of tobacco. The results indicated that the order of relational grades of main qualitative characters is the ratio of sugar and nicotine>total sugar>reductive sugar>the ratio of nitrogen and nicotine>K2O%>total nitrogen>protein>nicotine. The results will provide theoretical base to the design of the standard quality system of Yunnan Tobacco.