In order to improve the defense effect in network security, a research and implementation method of cloud computing network security virtual computing and defense technology is proposed. This architecture makes full use of the structural advantages of the virtualized environment, which can realize the trusted measurement of the user’s virtual machine in a more reliable way and can support the user’s diverse authentication requests. This paper introduces the concept of cloud computing, the classification of cloud computing, and the characteristics of cloud computing network security. In the case of fully considering the coupling relationship between the physical network and the logical network, the topology of the cloud computing network is established, and based on the network topology, the relevant network theory is used to analyze the cloud computing network. The avalanche failure under the computing network is studied. The research results show that the relative performance under different trusted measurement periods can reach more than 97%, which can flexibly meet the needs of user trusted authentication and can effectively provide trusted protection for user virtual machines. Adding additional protection measures to some special nodes in the cloud computing network topology to ensure that they are not damaged when attacked can greatly improve the robustness of the entire cloud computing network topology, therby ensuring that the network can avoid the attack. A large area will not be paralyzed due to the avalanche effect, and at the same time, the function and topology of the network itself have not changed. This method can effectively improve the security protection effect in network security.