The method includes following key points: when the method establishes LSP, entrance LSR or transmit LSR carries service quality parameter (SQP) relevant to resource allocation in Path message; after receiving Path message, transmit LSR puts apart bandwidth resource for traffic flow based on SQP; after LSP is established, transmit LSR of receiving traffic flow determines bandwidth of traffic flow put apart, and forwards traffic flow according to bandwidth put apart. The invention also discloses system for implementing DS-TE of MPLS network. The system includes entrance LSR, transmit LSR, and exit LSR. Thus, the invention can allocate bandwidth resources based on different types of traffic flow, and further can thin granularity of traffic flow engineering.