Abstract: Proposes a new dynamic routing algorithm of weight allocation for MPLS networks, taking mainly the hops, demands for bandwidth fragment and idle bandwidth rate into account to allocate rationally the bandwidth resource for incoming traffic. After implementing the routing selection at the border of MPLS networks, the explicit routing technique in MPLS is used to get rid of the effect of routing algorithms at middle nodes so as to give an LSP that will meet QoS requirements of all kinds of services. The simulation results indicated that the new algorithm can balance the traffic better, decrease the congestion in networks, utilize sufficiently the network resources by decreasing bandwidth fragment and enhancing the utilization of bandwidth and guarantee QoS to a certain extent by improving some parameters such as the losing rate.