The influence factors of the stability of karst cave under highway roadbed contain fuzzy information and the influence grade is not same. Based on the exploration data of a practical engineering

combined with the analytic hierarchy process (AHP) and fuzzy multiple attribute decision making (FMADM)

a model of fuzzy multiple hierarchy multiple attribute making for stability evaluation of karst cave under roadbed is set up. Then the advise of the weight matrix elements of analytic hierarchy process fuzzy conversion which proposed by Laagoven & Buckley is adopted and the formulas of vectors calculation is educed when the weight matrix elements is triangle fuzzy number. The fuzzy utilities of every comment are gained by using fuzzy swing average weight (FSAW). Finally

appraisement of karst cave fuzzy sets is gained by ordering the fuzzy sets. The results of engineering application demonstrate the feasibility and validity of the method

which provide a new idea and method for stability evaluation of the roadbed in karst region.