Abstract: In this paper,a multiple factors synthetical evaluation method of bits is given by using the fuzzy mathematics,The synthetical evaluation is conducted with the field information for 36 wells in the Lunnan oil field,Talimu,The results are compared with the selection model method s according to the drilling cost per meter and the compatibility rate reaches 86%.In this paper,the study about the expert evaluation mechanism and the quantitative description about the expert evaluation with the entropy can provide on effective method for the determination of the weighted vector.