The present invention relates to a method, an apparatus and a system for a group session service in a software defined network, and relates to the field of the wireless communication and particularly to a group session service. By separating service control signaling from service data, the demands for a Push to talk over cellular (PoC) server is low and little change is made on a service flow, no extra demands for a user is needed, the control logic of the group call service is simplified, the load of the PoC server is reduced, and the delay of a multiple-party session is remarkably reduced, thereby effectively improving the QoE of the user.