Software-defined networking (SDN) supports flexibly routing and switching by splitting the control plane and data plane in network devices. However, the security resource utilization now in SDN is inefficient, especially in the process of routing path construction. In this paper, we present a novel model for SDN controller to construct secure routing paths based on Network Security Virtualization (NSV) and the latest network status. Our new scheme considers various security devices' functionalities and the trust of different network devices in routing path establishment. We also introduce an identity-based authentication module to ensure the legitimacy of routing policies in SDN. We implement the prototype system, NSV-GUARD, and conduct theoretical analysis and performance evaluation. The results demonstrate that our approach can optimally utilize existing security devices and mechanisms in SDN. In addition, NSV-GUARD can efficiently verify malicious and fake routing policies generated by unregistered routing applications.