Cloud computing technology will provide application that needs many resources and various services to customers without any restriction of time and place. So, many of companies are now adopting cloud computing technology to this business and this trend is now increasing. However, cloud technology adoption rate is low because of security, compatibility, loss of control, security, data protection, performance and uptime, to the risk of vendor lock-in Cloud computing services, and compatibility with existing systems and anxiety. Now, many people are interest on the migration of existing systems but there are many study on this issue. So, more of study on this issue should be needed. This paper will show you the method that how to adopt cloud computing to their business and also show you evolution of cloud computing for existing system.