Cloud data center is becoming more and more important for tenants because cloud resources and associated services can be shared by multi-tenant. Although resource isolation and traffic control, which are effective ways to protect the QoS of tenants, have been used extensively, the topology of the network needs to be further studied extensively. In this paper, combining VN with SDN, a topology-aware VSDN embedding approach, named ToVSDN, is proposed to enhance the topology management. Extensive experimental evaluations have been conducted and the results verify that the proposed ToVSDN has improved embedding efficiency and obtained a higher revenue/cost ratio in comparison of correlative algorithms.