A new topology algorithm is proposed for remote real-time monitoring of the distribution network main wiringdiagram. The source-flow line of multi-source distribution network is described，and the source-flow chain and its properties aredefined. The source-flow chains are classified into unidirectional， bidirectional and multidirectional source-flow chains accordingto the distribution network topology graph. Accordingly， a gradual deepening strategy for source-flow chain tracking is adoptedfollowing the unidirectional， bidirectional and multidirectional simultaneous tracking. Chain data and the attribute domainmodel are developed based on directivity and motility of the source-flow chain. Comprehensive skills including sub-sectiontracking and checkpoints setting are used in the new method to improve the tracking efficiency. The new method has been usedin topology analysis of the tele-control of a railway power system.