Abstract: Cloud computing is an advanced emerging technology. The cloud environment is a large open distributed system. It is important to preserve the data, as well as privacy of users. And cloud computing is an efficient solution for the easiest and fastest storage and retrieval of data. The main issue in cloud computing is the data security. So here introducing a well defined security method in cloud computing environment. To implement this technique here adopted a method that is attribute based encryption with hierarchical structure of users.