The invention discloses a source node selecting method, comprising: the step S102, dividing the network into a plurality of partitions, respectively arranging a management server for managing related information in the partitions for each partition of the plurality of partitions; the step S104, transmitting request to the management server in the partitions by the request node in the network, to obtain data; the step S106, finding the source node with service ability and the shortest distance with the physical network of the request node by the management server of the partitions, and informing the found source node to the request node; and the step S108, transmitting the obtained request to the source node by the request node, and obtaining the data. According to the invention, starting delay is shortened, the number of the detecting information is reduced as much as possible, and cross-regional flow is reduced, thereby advancing utilance of the network.