A transmission processing method, comprising: receiving from a user interface a transfer request for transferring a flow on a transmission path where link congestion occurs to a preset path to transmit the flow, wherein the preset path is one of preset equal-cost multiple paths, ECMPs, of the transmission path; and according to the transfer request, transferring the flow on the transmission path where link congestion occurs to the preset path to transmit the flow; wherein the step of transferring, according to the transfer request, the flow on the transmission path where link congestion occurs to the preset path to transmit the flow, comprises: for an Access Control List, ACL, of each device in the preset path, sending to the ACL a first flow rule which defines a count action; for the ACL of the each device in the preset path, sending to the ACL a second flow rule which defines an output port; and according to the first flow rule and the second flow rule, transferring the flow on the transmission path where link congestion occurs to the preset path to transmit the flow; and wherein before receiving from a user a transfer request for transferring a flow on a transmission path where link congestion occurs to a preset path to transmit the flow, the method further comprises: receiving setting information for setting a flow path by the user, wherein the setting information comprises: Virtual Routing Forwarding, VRF, a source IP subnet/mask, a source port, a source switch, a destination IP subnet/mask, a destination port, a destination switch, or a protocol, wherein the protocol comprises any one of a Transmission Control Protocol, TCP, a User Datagram Protocol, UDP, an Internet Control Messages Protocol, ICMP, an Open Shortest Path First, OSPF, protocol, a Stream Control Transmission Protocol, SCTP, a Datagram Congestion Control Protocol, DCCP, and a Multipath Transmission Control Protocol, MPTCP, setting the flow path according to the setting information; and calculating the preset equal-cost multiple paths of the flow according to a setting result. receiving from a user interface a transfer request for transferring a flow on a transmission path where link congestion occurs to a preset path to transmit the flow, wherein the preset path is one of preset equal-cost multiple paths, ECMPs, of the transmission path; and according to the transfer request, transferring the flow on the transmission path where link congestion occurs to the preset path to transmit the flow; wherein the step of transferring, according to the transfer request, the flow on the transmission path where link congestion occurs to the preset path to transmit the flow, comprises: for an Access Control List, ACL, of each device in the preset path, sending to the ACL a first flow rule which defines a count action; for the ACL of the each device in the preset path, sending to the ACL a second flow rule which defines an output port; and according to the first flow rule and the second flow rule, transferring the flow on the transmission path where link congestion occurs to the preset path to transmit the flow; and wherein before receiving from a user a transfer request for transferring a flow on a transmission path where link congestion occurs to a preset path to transmit the flow, the method further comprises: receiving setting information for setting a flow path by the user, wherein the setting information comprises: Virtual Routing Forwarding, VRF, a source IP subnet/mask, a source port, a source switch, a destination IP subnet/mask, a destination port, a destination switch, or a protocol, wherein the protocol comprises any one of a Transmission Control Protocol, TCP, a User Datagram Protocol, UDP, an Internet Control Messages Protocol, ICMP, an Open Shortest Path First, OSPF, protocol, a Stream Control Transmission Protocol, SCTP, a Datagram Congestion Control Protocol, DCCP, and a Multipath Transmission Control Protocol, MPTCP, setting the flow path according to the setting information; and calculating the preset equal-cost multiple paths of the flow according to a setting result. for an Access Control List, ACL, of each device in the preset path, sending to the ACL a first flow rule which defines a count action; for the ACL of the each device in the preset path, sending to the ACL a second flow rule which defines an output port; and according to the first flow rule and the second flow rule, transferring the flow on the transmission path where link congestion occurs to the preset path to transmit the flow; and wherein before receiving from a user a transfer request for transferring a flow on a transmission path where link congestion occurs to a preset path to transmit the flow, the method further comprises: receiving setting information for setting a flow path by the user, wherein the setting information comprises: Virtual Routing Forwarding, VRF, a source IP subnet/mask, a source port, a source switch, a destination IP subnet/mask, a destination port, a destination switch, or a protocol, wherein the protocol comprises any one of a Transmission Control Protocol, TCP, a User Datagram Protocol, UDP, an Internet Control Messages Protocol, ICMP, an Open Shortest Path First, OSPF, protocol, a Stream Control Transmission Protocol, SCTP, a Datagram Congestion Control Protocol, DCCP, and a Multipath Transmission Control Protocol, MPTCP, setting the flow path according to the setting information; and calculating the preset equal-cost multiple paths of the flow according to a setting result.