Abstract: This paper proposes a multi-agent network security risk assessment model based on attack graph.Firstly,this paper proposes the architecture of multi-Agent risk assessment and gives the function design of main modules for main and subsidiary Agent.Multi-Agents are adopted to generate attack graph synergistically by using the components of network hosts as the basic nodes.Secondly,five risk indexes are defined and the method to compute the risk index of network security is given.Finally,the network security risk assessment model is performed based on the Java Agent Development Framework (JADE),and a risk assessment experiment with simulation network is conducted.The experimental results prove that our model is a feasible and effective approach to the network security risk assessment.