The main contribution of this research is to present the method that make it possible to assess the vulnerability in the information infrastructure using simulation technology. To construct the vulnerability assessment simulation system, we make use of the knowledge-based simulation modeling methodology and we designed expressions to estimate the degree of vulnerability of host. Also, we show newly defined vulnerability analysis method that is applicable to vulnerability assessment simulation system. As research results, the vulnerability assessment simulation system and VDBFS(Vulnerability DataBase For Simulator) are constructed.