Cloud Computing becomes the next generation architecture of IT Enterprise. In contrast to traditional solutions, Cloud computing moves the application software and databases to the large data centers, where the management of the data and services may not be fully trustworthy. This unique feature, however, raises many new security challenges which have not been well understood. In cloud computing, both data and software are fully not contained on the user’s computer; Data Security concerns arising because both user data and program are residing in Provider Premises. Clouds typically have a single security architecture but have many customers with different demands. Every cloud provider solves this problem by encrypting the data by using encryption algorithms. This paper investigates the basic problem of cloud computing data security. We present the data security model of cloud computing based on the study of the cloud architecture. We improve data security model for cloud computing. We implement software to enhance work in a data security model for cloud computing. Finally apply this software in the Amazon EC2 Micro instance.