SDN (software-defined network) realizes the separation of control and forwarding, and effectively solves the problem of flexible allocation of network resources. Based on the application of SDN in data center network, this paper analyzes the technical characteristics of modern data center network and SDN. At the same time, this paper designs the application architecture of SDN in modern data center network. Then this paper analyzes and summarizes the routing performance requirements of data center network based on SDN from the perspective of routing, and puts forward the corresponding solutions. The scheme in this paper makes up for the shortcomings of cloud computing in network virtualization. In this paper, computing, storage and network are further integrated to realize fully automatic resource deployment, real-time resource scheduling and fast network troubleshooting in a real sense. This method has the potential to add new services at any time and accelerate the pace of network innovation. This method provides a new option for cloud computing center operators to reduce maintenance costs and improve user experience.