Multicast transmission is a key technology in Internet, which can send the same information simultaneously to several receivers. A new multicast routing algorithm based on network coding is proposed in this paper, searching the routing groups from source to each receiver by using Dijkstra reduction network. Simulation results show that, compared with traditional multicast routing algorithms, performances of the routing algorithm are improved at a great extent in resource consumption and load balance, and are closer to minimum-cost multicast algorithm based on network coding. Finally, mathematic analysis indicates that the algorithm has lower computational complexity.