The invention relates to a P2P stream media playing method and system based on request forwarding. The method comprises the following steps that a data request node in a P2P network asks a data providing node for data, and when the data providing node judges to know that not all data slices required by the data request node can be sent due to insufficient uplink bandwidth, the next step is carried out; and the data providing node starts a request forwarding strategy to provide required stream media data for the data request node. The request forwarding strategy is used in a single channel, and concretely provides data to the data request node through a node which has sufficient uplink bandwidth and is located in the single channel with the data providing node; or when the data providing node is located in a cold broadcast channel, the request forwarding strategy can also be used in the channel, and data is provided to the data request node through the node in some hot broadcast channel. The node provided by the invention can quickly acquire data, the utilization rate of the uplink bandwidth of the node is effectively improved, and the robustness of the system is improved.