Reliability and stability are essential to Media-on-Demand (MoD) system. Based on the node reliability and QoS assessment, a Peer-to-peer MoD architecture (RP2MoD) is proposed in this paper. In the proposed system, the reliable degree of each client is calculated based on the failure probability of its parents, and the QoS level of its parents is also assessed. The reliability degree and QoS level are the basis of MoD operations, such as the parent selection, the allocation strategy of the requested media data and the error resilience. Analytical and experimental results about the system performance show that the operations relative to the reliability degree and QoS level have little effect on the performance of the proposed system and result in a strong ability of fault tolerance. Thus the system can provide large-scale, steady and reliable MoD service in Internet.