Software-Defined Networking (SDN) and Network Function Virtualization (NFV) are emerging as promising innovations for future network, which make Virtual Network Service (VNS) possible to be implemented broadly. It is the common truth that VNS is realized by the collaborations of multi-providers in practical scenario, where potential risks are lying in the collaborations. The primary risk is the availability of VNS. How to composite high available SDN/NFV-based VNS by multi providers is a fundamental problem for practical applications. In this paper, a high available SDN/NFV-based VNS scheme in multi-provider scenario is presented. This paper discusses the motivation concerning availability of VNS and presents a scheme to provide high available SDN/NFV-based Virtual Network Service in multi-provider scenario. The architecture of SDN/NFV integration and network service composition with certain security mechanism using the SDN/NFV integration in multi-providers scenarios are illustrated, which make an emphasis on availability of VNS. A use case is proposed to illustrate the features and advantages of the proposed scheme.