Abstract: Continuous media service is a new kind of real time applications. It requires that hard and soft real time tasks should be supported in an integrated operating system framework. But the scheduling policies in traditional OS（e.g., UNIX or Windows NT）can’t support this application to the best. This paper proposes a new QoS method, based on which a QoS based heuristic task scheduling algorithm supporting continuous media streams is described. The algorithm takes into account the success ratio and consecutive fail count of multimedia tasks in order to guarantee the quality of all media streams. Finally, simulation and comparison are performed to validate the effectiveness of this algorithm.