The application and development of computer technology have driven and promoted the change of information technology. The computer and information technology have a wide range of penetration and affinity, which influences the world economy and social development in all aspects. In twenty-first Century, the human life will be more closely linked to the Internet, and more closely related, such as electronic commerce, information platform, etc. However, all kinds of problems arise, for example, there are many threats and attacks existing in the Internet, making the network security damaged, which can cause the disclosure of information, and the system platform and the network resources are under attack. In consequence, in terms of how to ensure the information is sent and received truly, completely, effectively and legally, the issue of network security has become a current research hot-spot. This paper, in allusion to this problem, introduces and analyzes several typical computer network security technologies, including firewall technology, virus protection technology, and virtual private network technology, also called VPN technology.