Abstract: Grading the degrees of plant risk is a very important base of assessment for preference conservation of rare and endangered plants. A microcomputer quantitative system for grading the risk index of the 100 species in China was established . After the calculation of'fuzzy comprehensive evaluation (FCES) and fuzzy comprehensive evaluation values (FCEV), the "grading of risk size" was calculated by the fuzzy system type distinguishing (FSTD). The result shows that the system is highly accurate and its manipulation is comparable to the current qualitative assessment in reflecting the actual endangered situation of the 100 plant species in China.

Key words: Risk size, Rare and endangered plants, Systemtype distinguishing, Fuzzy comprehensive evaluation values