Abstract：Multicast routing algorithm is extremely important to the communication performance of interconnection network and multiprocessor systems. Taking into account the performance, cost and implementation difficulty, a new tree-based restricted multicast routing algorithm named TRMA was presented for Triplet-based Hierarchical Interconnection Network (THIN). TRMA fully used the hierarchy of network and the topology information included in the nodes codes to decide the message routing, which can make the design of algorithm very simple and hardware implementation easy. Compared with other tree-based multicast routing algorithms, TRMA need not to construct multicast tree in source node before transferring a multicast destination message and can improve the system performance. A simulation has been conducted that compares the performance of TRMA and unicast-based multicast algorithms in THIN. The results indicate that TRMA is more suitable for multicast routing in THIN with lower latency and traffic.