Abstract: According to the characteristic of the network attack-defense real-time variation,a dynamic assessment method of network security state was presented．Firstly,a network security model based on vulnerability state transition was built,according to the characteristics of attack and defense both sides．Then the success probability and the consequences of attack success were quantitated,and the effects of attack-defense confrontation behaviors on the key asset security attributes such as confidentiality,integrity and availability were analyzed．Finally,the feasibility and validity of this method were proved through an experiment.

Key words: Attack graph,Security assessment,Visualization,Attack-defense confrontation