Abstract: The new moon-like downfaulted zone consisting of Tangyin fault, Jiyuan fault and Luoyang fault shows similar tectonic characteristics with Fenwei downfaulted zone. The downfaulted zone is an active fault zone, a fault basin zone and a seismic active zone, and it formed an active margin between fault blocks. Recently, though the seismicity in this region is weak, the region possesses tectonic conditions for occurrence of moderately strong earthquakes, so the seismic observation and the research work in the region should be done well.