Abstract: The present invention discloses a system for ensuring network quality of service (QoS), comprising: a QoS service controller (QSC) for extracting QoS request to network from service request, transmitting the QoS request to a DRC resource controller in the network, and transmitting resource-releasing information; a QoS pipe provisioning controller (QPPC) for provisioning pipes, obtaining information about the resource occupation condition of QoS pipes periodically, and adjusting the capacity of the pipes dynamically but not by real-time; a distributed resource controller (DRC) for processing the QoS request from the QSC dynamically, and implementing access control and resource distribution of each resource request. Based on this system, the invention also provides a method for distributing network resource in a layered way.