The application discloses a bandwidth setting method, device and system. A specific embodiment of the method comprises the following steps: acquiring a bandwidth overflow value of a data transmission link, wherein the bandwidth overflow value is the difference value between the bandwidth occupied by the data transmission link and a preset maximum allowable occupied bandwidth; acquiring the bandwidth occupied by each data flow in the data transmission link, and determining the priority of each data flow; re-distributing the bandwidth for the data flows in the data transmission link according to the bandwidth overflow value, the bandwidth occupied by each data flow and the priority of each data flow, and generating bandwidth distribution information corresponding to the data flows, wherein the bandwidth distribution information comprises a bandwidth distribution instruction; and respectively sending the bandwidth distribution information corresponding to the data flows to clients corresponding to the data flows so that the client can set the bandwidth for each data flow in the data transmission link according to the bandwidth distribution instruction. Through the adoption of the method, device and system disclosed by the embodiment, the effective and reasonable bandwidth distribution is realized.