As an important product of the combination of computer technology and the Internet, cloud computing has opened a new round of technological revolution in the field of IT and information. However, cloud computing has a lot of risk problems. There are still many vulnerability problems under the current regulatory network environment, producing a huge threat for the information security of the network users. In order to solve this problem, it is imminent to carry out the user authentication security analysis in the background of cloud computing. This paper will focus on the cloud computing security problems and puts forward some specific measures.