Abstract: Mr. Zhang Jiafa, a staff in the Cultural Museum of Maguan county, sent a piece of fossil mammalian maxilla with four cheek teeth (P3-M2) to IVPP in August of 1989. Having compared to other species of Gigantamynodon, I found that the specimen represented a new species in that genus. Its discovery locality is the south most one of the Paleogene mammalian localities of China. Apparently the specimen was collected from coal mine because it was surrounded by the coal. The age of the mammal is considered to be of Middle or Late Oligocene. It will be difficult for us to tell the further exact age because there is no other evidence.