As the increasing development of application technology and infrastructure, many kinds of application and resources can be encapsulated as web service and its variations, and service-oriented computing become research hot. But, we believe service-oriented computing should establish on virtualized service rather than concrete service instance directly. In this paper, we present formalized model of virtualized service and service instance, and define the concept of service virtualization. Then, we propose the implementation solution of virtualized service- oriented application from perspective of global and local instantiation process.