Cloud computing technology has become the current focus on the development of information technology. The economic effect for cloud computing has gained widespread acceptance. At the same time, security has emerged as arguably the most significant barrier to faster and more widespread adoption of cloud computing. Therefore, the point of cloud computing security is to research the key technology of the cloud security and propose a powerful security solution, which includes a reasonable cloud computing security model and reliable security strategy. In order to build an in-depth security defense system for cloud computing applications, the needs of the cloud computing security are analyzed, a cloud computing security model and strategy is proposed in this paper.