Abstract
Cyberspace is a complicated system of computer, network and other information environments. To evaluate its security defence ability, the offensive and defensive features in cyberspace were discussed in this paper, firstly. Then index system and evaluation model were proposed. Based on analytic hierarchy process method, cyberspace security defence system was decomposed from its ability aspect. Fuzzy theory and information entropy weight coefficient method were applied to solve the complexity and uncertainty of the defence effectiveness. The study indicates that this evaluation model can objectively and effectively evaluate the cyberspace defence effectiveness, and lay the foundation for the promotion of cyberspace security defence ability.