Cloud computing is one of today's most exciting technologies due to its ability to reduce costs associated with computing while increasing flexibility and scalability for computer processes. Cloud computing is Internet-based computing, whereby shared resources, software and information, are provided to computers and devices on-demand, like the electricity grid. It aims to construct a perfect system with powerful computing capability through a large number of relatively low-cost computing entities, and using the advanced business models. The construction of on-premises application platform into cloud environment with limited foundations, infrastructure and application services. The integration of cloud platform architecture and on-premises platform together is an enormous reform on building a huge environment on today's cloud computing environment. SOA is a set of services and advocate the principles of component reuse and well defined relationship between a service provider and service consumer. This article introduces the background, services and service model of cloud computing and overlapping of SOA and cloud computing.