A method for maintaining multicast group members performed by a Software Defined Network, SDN, controller, the method comprising: • sending a query message to a SDN switch at intervals of a preset period (S 201); • receiving a count value of current period query responses of a current period from the SDN switch (S 202); and • maintaining, according to the count value of current period query responses and a count value of previous period query responses, the multicast group members comprised in the multicast group, wherein the maintaining, according to the count value of current period query responses and the count value of previous period query responses, the multicast group members comprised in the multicast group comprises: acquiring a preset query response count value increment corresponding to the multicast group from a stored correspondence between a multicast group address and the preset query response count value increment, wherein the preset query response count value increment is an actual quantity of multicast group members included in the multicast group in a previous period; calculating a difference between the count value of current period query responses and the count value of previous period query responses; and maintaining, according to a comparison of the difference with the the preset query response count value increment, the multicast group members comprised in the multicast group. • sending a query message to a SDN switch at intervals of a preset period (S 201); • receiving a count value of current period query responses of a current period from the SDN switch (S 202); and • maintaining, according to the count value of current period query responses and a count value of previous period query responses, the multicast group members comprised in the multicast group, wherein the maintaining, according to the count value of current period query responses and the count value of previous period query responses, the multicast group members comprised in the multicast group comprises: acquiring a preset query response count value increment corresponding to the multicast group from a stored correspondence between a multicast group address and the preset query response count value increment, wherein the preset query response count value increment is an actual quantity of multicast group members included in the multicast group in a previous period; calculating a difference between the count value of current period query responses and the count value of previous period query responses; and maintaining, according to a comparison of the difference with the the preset query response count value increment, the multicast group members comprised in the multicast group. acquiring a preset query response count value increment corresponding to the multicast group from a stored correspondence between a multicast group address and the preset query response count value increment, wherein the preset query response count value increment is an actual quantity of multicast group members included in the multicast group in a previous period; calculating a difference between the count value of current period query responses and the count value of previous period query responses; and maintaining, according to a comparison of the difference with the the preset query response count value increment, the multicast group members comprised in the multicast group.