Embodiments of the present invention provide a service gateway, comprising a service session detection unit adapted to detect a service session request and the end of a service session. The service gateway further comprises a QoS negotiation unit, adapted to acquire quality of service (QoS) information of a service session after the service session request is detected by the service session detection unit, request corresponding service serving network resource according to the QoS information, and trigger to release the service serving network resource when the end of the service session is detected by the service session detection unit. In addition, the embodiments of the present invention also disclose a corresponding service serving system, QoS negotiation and service serving network resource release method. The present invention could implement a QoS request process without the participation of a terminal. Embodiments of the present invention are conveniently to be deployed and implemented, and the peer-to-peer QoS can be quickly deployed and implemented without changing the current network service server.