In Internet of things, lots of instruments and sensors will connect into Internet and can be controlled through Internet to achieve Smart Planet. One of the key challenges is to integrate instruments and sensors into business process. SOA is an ideal infrastructure for business process management and lots of business process definition languages are now available for process orchestration. Instruments functions are encapsulate to web services and can be organized with other web services equally. But these device-oriented web services are different from common web services because devices can't be controlled by more than one client at the same time. This feature can't be supported in traditional process definition languages. In this paper, a new process definition langue for Internet of Things is provided. It is an XML-based language; the structure of the language includes 3 sections: services, sequence and vars. Services section is used to describe service information. Device-oriented web services and common web services are described in this section. Sequence section is the main body of the process, which includes the specific business process of the IoT application. Sequence is used to enable executing several commands in order. © 2012 IEEE.