Abstract: The Miomoptera is a small extinct fossil order, distributed in the Germany (C2), Czech, Middle Asia, Russia and American (P), but it had not been discovered in China. In 2000, the authors found a new genus with a new species, collected from the Midtriassic, grayish-green mudstone and shale of the Upper part of the Lower Member, Midtriassic Tongchuan Formation (T2t) in Tongchuan region of Shaanxi Province, China. According to the historical references of this order Miomoptera, the discovered fossil in world is rare, and it has known only 3 families and 10 genera and are reported. The discovery of the new fossil Triasomiomopteris oblongata gen. et sp. nov fills in the gap in the field of China and of the Midtriassic Miomoptera in the world, and has certain important reference value for the evolution of Miomoptera from the Late Paleozoic to Early Mesozoic eras.