Security Evaluation System is a system that evaluates the security of the entire enterprise network domain which consists of various components and that supports a security manager or a Security Management System in making decisions about security management of the enterprise network based on the evaluation. It helps the security manager or the security management system to make a decision about how to change the configuration of the network to prevent the attack due to the security vulnerabilities of the network. Security Evaluation System checks the “current status” of the network, predicts the possible intrusion and supports decision-making about security management to prevent the intrusion in advance. In this paper we analyze the requirements of the Security Evaluation System that automates the security evaluation of the enterprise network which consists of various components and that supports decision-making about security management to prevent the intrusion, and we propose a design for it which satisfies the requirements.