Aspects such as multiple influencing factors,complicated hierarchical structure,and relation between indicators perplexed the vulnerability evaluation target system for wireless network.This paper proposes a method to construct target system of vulnerability evaluation based on knowledge reduction.Firstly,a primary target system of vulnerability evaluation for wireless network is established,hence the decision table of vulnerability evaluation is constructed.Secondly,the knowledge reduction is employed to simplify the decision table,and arithmetic of character vector is used to sort the significance of non-core targets.Premised on high accuracy of evaluation result,this proposed method is more objective than AHP weight judgment method.Finally,this knowledge reduction based method is comparatively analyzed with AHP weight judgment method to validate its feasibility.