The present invention discloses a method for acquiring media stream Quality of Service (QoS) periodically. The MGC sets an inspect duration during which the MGC periodically acquires the QoS information of the media stream, thereby timely acquiring the QoS information of the media stream and effectively controlling the media stream. Two ways for the MGC periodically acquiring the QoS information are provided. The MG actively submits the QoS information to the MGC and the MG submits the QoS information to the MGC according to the periodic request of the MGC. The embodiment of the present invention provides the capability of adjusting the call microscopic QoS, enhances the real-time quality of evaluating the QoS and that of dynamically adjusting call control strategy, inherits the ability of the original protocol for evaluating the microscopic QoS of the network during a certain period and provides more accurate evaluation.