As a new method of computing, cloud computing has brought great convenience to people's network life, but at the same time, there are some security risks.This paper briefly introduces the concept and characteristics of cloud computing, and briefly analyzes the significance to study the security of computer network in the environment of cloud computing, and briefly analyzes the security vulnerabilities in this environment according to the characteristics of cloud computing, to research and put forward the corresponding measures to strengthen the security.Twenty-first Century is the information age, information technology has become a pioneer force in the development of the times, with the deepening of the globalization process, the Internet has also become a bridge to connect the world, and a large number of resources and data have been shared through the network.The emergence of cloud computing has accelerated the process of data processing and sharing.However, the development of new technology has also brought new security risks.Therefore, the problem of computer network security in the environment of cloud computing is also getting more and more attention.