The present invention discloses a method for guaranteeing reliability of end-to-end QoS, including: a. detecting and determining whether there is a failure on a Label Switched Path (LSP); if there isn't, returning to the process of detecting; otherwise, determining whether there is a backup LSP for the failed LSP; if there is, an edge router or a transmit router switching service streams and corresponding resources from the failed LSP to the backup LSP based on a certain policy; otherwise, a resource control function (RCF) entity allocating a new LSP according to network topologies for the service streams born on the failed LSP, and switching the service streams from the failed LSP to the newly allocated LSP, and releasing the path resources formerly occupied by the service streams. The method can guarantee service continuity and reliability of QoS in a bearer network.