The invention discloses a packet scattering based heterogeneous stream isolation method in a DCN (Data Center Network). When an IP (Internet Protocol) subgroup is received, an exchanger can judge that whether the stream class of a stream to which the subgroup belongs is a long stream or a short stream according to a stream length threshold value, and then selects a corresponding forwarding path for a current subgroup according to the stream class and the transmission state of the short stream. Different paths are distributed for long-stream and short-stream subgroups to carry out transmission; the resource competition and conflict of a heterogeneous stream are avoided. By using the packet scattering based heterogeneous stream isolation method, the completion time of a delay-sensitive short stream in a data center can be shortened; meanwhile, the throughput rate of a throughput-sensitive long stream is maximized; therefore, the application performance is promoted; the user experience is optimized.