Abstract: In MPP networks, virtual channel is used to prevent deadlock and improve throughput.Without considering the traffic on different virtual channels,normal virtual channel assignment algorithms are likely to cause traffic imbalance,which decreases the network performance.In this paper,Torus network is studied under wormhole routing technology and dimension ordered routing algorithm,and a virtual channel assignment algorithm ORA is proposed for traffic balance. Compared with Naive and Scott virtual channel assignment algorithm, ORA algorithm has a better performance for traffic balance,and can improve the network performance.