Attack and defense are dialectical unity， and their mutual transformation is a direct embodiment of the combat process. In network attack and defense， the offense usually dominates while the defense is in a relatively weak position， and the idea of dynamic defense is valued. By combing and analyzing the dynamic defense of cyberspace， the factors affecting the defense capability of cyberspace are obtained， and a set of cyberspace defense index systems based on dynamic empowerment is constructed. To eliminate the interference of human preference on the results， the entropy weight method is adopted to simplify the index set， and the comprehensive weight of each index is weighted. The TOPSIS（technique for order preference by similarity to an ideal solution）-gray correlation analysis method is applied to construct an evaluation model to realize the evaluation of cyberspace defense capability， and the effectiveness and feasibility of the evaluation model are proved by specific cases.