Web service is an emerging software technology to use remote services in the Internet. As it becomes pervasive, some "language" to describe Web service flows is needed to combine existing services flexibly. The flow essentially describes distributed collaborations and is not easy to write and verify, while the fault that the flow description may contain can only be detected at runtime. The faulty flow description is not desirable because a tremendous amount of publicly shared network resources are consumed. The verification of the Web service flow prior to its execution in the Internet is mandatory. This paper proposes to use the software model-checking technology for the verification of the Web service flow descriptions. For a concrete discussion, the paper adapts WSFL (Web Services Flow Language) as the language to describe the Web service flows, and uses the SPIN model-checker for the verification engine. The experiment shows that the software model-checking technology is usable as a basis for the verification of WSFL descriptions.