A flow entry delivery method and a communication system are provided. The communication system includes a controller and N switches. After receiving a packet-in message sent by a source switch, the controller determines a forwarding path for forwarding to-be-forwarded data. Then, the controller generates a corresponding flow entry for each of the N switches in the forwarding path separately, and generates a corresponding control instruction for each of other N−1 switches except the source switch in the forwarding path separately. After encapsulating the generated N flow entries and N−1 control instructions into the Nth command packet, the controller sends the Nth command packet to the Nth switch of the N switches, so that the Nth switch transmits the N flow entries in the forwarding path according to the Nth control instruction in the Nth command packet.