Abstract: An explicit routing algorithm based on policy and traffic classification was proposed. The algorithm was implemented in two steps: offline and online computation. The process of offline computation outputted the bandwidth for each type of traffic flow and the algorithm was based on multi-commodity problem, which got the minimum network resource consumption while meeting the bandwidth demands for all kinds of traffic flows in the network. The process of online route computation outputted the shortest path for each flow according to the pre-allocated bandwidth values of the offline process. The combination of offline and online computation mapped the traffic flows to the network topology according to the traffic distribution property, and thus could alleviate the performance degeneration problem existing in the traditional routing algorithms. The network traffic distribution state, resource situation and network management policy were taken into consideration in the process of explicit route computation, which could improve the utilization of network resource and provide the explicit route for facilitating MPLS traffic engineering and traffic control effectively.