With the rapid development of science and technology and the network popularization, computer network security becomes a social problem. Based on the analysis of the main factors influencing the computer network security, the risk evaluation index system of computer network security is established. The analytic hierarchy process (AHP) is used to calculate the weight of each index. Through the common criteria to determine the grey clustering of computer network security risk, establishing the whitenization weight function of computer network security risk evaluation model, and then calculating the whitenization clustering coefficient and clustering vector of computer network security risk evaluation model, the evaluation results are finally obtained. The method is scientific and reasonable, combining subjective evaluation with objective calculation.