Disclosed is a method, system and device for searching active nodes in P2P(peer to peer) streaming media system. Selectable nodes briefly and efficiently report their own subblocks information to a tracker device, such as the number of the continuous buffered subblocks, the sequence number of the first subblock of the continuous subblocks and the total number information of the buffered subblocks; the tracker device can select suitable candidate nodes for a request node according to the subblocks information of the selectable nodes, therefore the request node can determine active nodes without sending a large amount of detections to the candidate nodes; the waste of communication resources is avoided and the bandwidth cost is reduced; also, the selectable nodes can report characters of the networks where they locate, and the tracker device can select nodes in wired network to be candidate nodes first, therefore, the transmission speed of the whole P2P system is improved and the waiting delay of the request node is reduced.