E-government cloud is a kind of big scale private cloud data center. It takes the SDDC as the architecture. For the software defined network, this paper firstly introduces the main characters of the e-government cloud and the challenges of the network, and then offers a solution based on VxLAN and SDN. It also gives a network overlay solution for the e-government cloud, and summarizes its advantages. It provides a scheme to connect the SDN controller to the heterogeneous cloud management platform. At last, taking Openstack as an example, the configuration process of SDN controller and cloud management platform are described.