On the basis of selecting the affecting factors, a fuzzy consistent matrix was formed by using fuzzy decision －making theory and the dangerous extent was quantified with integrated decision －making optimum value which was generated from the fuzzy consistent matrix. As an example, the sections of Shishou reaches whose parameters weremeasured in September, 1998, were quantitatively evaluated using the above method and the result showed that the bank － failure dangerous extent of Beimenkou section is higher than any other sections. The fact that the ba
nk section failed in October, 1998, proved that the evaluation result is correct， and that the method advanced in this paper is feasible and creditable. 