A software-defined data center, and a deployment method for a service cluster are described therein. An SDN controller manages a cluster by using a shared IP address. The SDN controller obtains an online virtual machine event that is sent by an edge switch accessed by a new online virtual machine; obtains a MAC address of the new online virtual machine, and identifies the new online virtual machine; then identifies whether an IP address of the new online virtual machine is a shared IP address; and if the IP address of the new online virtual machine is the shared IP address, deploys the new online virtual machine to a service cluster corresponding to the shared IP address. The SDN controller automatically completes creation, capacity expansion of the service cluster, so that no manual intervention from a tenant is required, and tenant experience is good.