A line card determination, determination processing method and device, and a line card determination system are provided, where the determination method includes: receiving a flow table entry and/or a group table entry containing a port number issued by a controller, where the port number is that of a service flow corresponding to the flow table entry and/or the group table entry; and determining a line card corresponding to the port number according to a pre-stored corresponding relationship between line cards and port numbers of various line cards in a data forwarding device. With the use of the above-mentioned technical solutions, the problem of wasting communication resources and line card resources, since the main control board cannot determine which specific line card the flow table entry or group table entry issued by the controller should be specific to, in the related art is solved, and the flow table entry or group table entry can be issued to only an associated line card through simple mapping, thereby significantly reducing waste of communication resources and line card resources.