Abstract: In order to find out the high risk area caused by unstable wind flow in the diagonal branches,an automatic recognized method of the high risk region in the coal mine was provided based on the subgraph isomorphism. The paper had an analysis on the topology structure features of the typical high risk region and the equivalent graph model of the high risk region was established. The attributed graph of the ventilation system in the mine and the equivalent specialization of the high risk region were realized. Based on the subgraph isomorphism calculation, the recognization method of the high risk region in the coal mine was established.High risk area in a complex ventilation network could be automaticly identified according to both structure and attributes of the roadway.With the recognization of the spontaneous combustion high risk region in the seam of Huangling No.2 Mine, the accuracy and efficiency of the method was approved.