With the rapid development of China's economy and the popularization of computer network technology applications, greatly accelerated the pace of the arrival of the cloud. Cloud computing is the new development of computing models after distributed computing, parallel processing, and grid computing. Cloud computing technology application level is in-depth, application areas continue to expand. With the popularity of cloud computing technology, cloud computing security has become an important issue affecting the application and development of cloud computing. Cloud computing technology will be computing resources, storage resources and other resources into a shared public resources, this technology also led to the lack of transparency and less control of IT assets, resulting in a lot of business concerns about data loss and destruction. At present, the main risks to cloud computing are risk of sharing risks, insecure interfaces, privileged user visits, identity counterfeiting, data security risks, management risks and legal risks. In view of the main risks of cloud computing, we adopt encryption technology, introduce strict identity authentication mechanism, strengthen management, safety supervision and improve the information security laws and regulations and other countermeasures, to solve the security problems brought by cloud computing.