Analytic Hierarchy Process(AHP),a qualitative and quantitative method for multi target decision, was first brought up by T.L.Saaty in 1970s. By using AHP, the author establishes a mathematic model of hierarchy relationship among competitive factors, evaluation indexes for performance and level of performance, To analyze influences of each competitive factor on performance and create arrangement of competitive factors in terms of importance to performance of enterprise own or rival firms, and ascertain core competence according to qualitative and quantitative analysis to support competitive decisions in markets. Finally the result of this research is applied to DaFeng Ltd. and its' feasibility and practicality in decision can be tested and verified.