Computer network vulnerability analysis is a method of analysis and evaluation of network security beforehand. The attacks method has occurred in the network, the previous network status change as input information, calculated by the model analysis. Forecasting network node may be network attacks given the current security level value network, network security reinforcement measures taken before the danger. Administrators can proactively identify network security issues, to take measures in advance to avoid information leakage, financial losses, ensure the safety of individuals and countries. Therefore, vulnerability analysis computer network is very important. Based on the properties of attack graph shows the method of attack graphs to Bayesian network transformation, using the new algorithm to eliminate loops attribute attack graph optimization, building the Bayesian attribute attack graph model used to evaluate the network itself security situation. In this model, based on Bayes formula for calculating the probability of a new node probability calculation formula and attack paths occur for calculating network vulnerability assessment of the quantitative indicators. The model not only can visually process description of cyber attacks, but also into the Bayesian network probabilistic thinking of possible network attack path prediction and assessment.