The invention relates to a P2P stream media data demand method and system based on feedback control. The system comprises a P2P node and a stream media providing server. A feedback control strategy is a process that information such as buffer mapping of an adjacent node, a data request received by the node, and data volume received by the node, which are generated during a node data scheduling and service scheduling process, is utilized to guide the next round of data request of the node, and the collected information is utilized to control an overlay network to replace the adjacent node. The feedback control strategy comprises the following steps: calculating priorities of the data slices through the node, distributing data requests through the node, collecting feedback information through the node, and feeding back to the overlay network through the node. The feedback control strategy can effectively solve the influence of dynamic nature on the system, the robustness of the system is improved, and the overall performance of the system is improved.