The invention relates to the technical field of SDN, particularly to an SDN-based data forwarding system and method. The system comprises an SDN controller and an SDN switch. The SDN controller generates a multicast forwarding table according to an IGMP control message from the SDN switch and issues a flow table to the SDN switch based on the multicast forwarding table; and the SDN switch forwards or abandons an IGMP data message according to the flow table. On the basis of the SDN architecture, the SDN controller generates the all-network multicast forwarding table according to the IGMP control message and issues the flow table based on the multicast forwarding table, and the subsequent multicast flow is forwarded based on the flow stable, so that all-network multicast controlling is realized.