Madoi-Gade fault is an active fault in the Bayan Har block. According to field investigation, there is an earthquake surface rupture fairly well preserved on the Gade segment of the Madoi-Gade fault zone. The length of the rupture is approximately 50km, with a general strike of NW. The maximum horizontal sinistral displacement is about 7.6m and the maximum vertical displacement is about 4m. A large number of earthquake traces are to be found along the rupture zone, and the phenomena on the surface rupture are also various. Field investigation and analysis on the geological and geomorphological phenomena show that the formation age of the surface rupture is relatively young. A series of linear arranged, triangular facets, fault scarps, fault springs, dislocated gullies, twisted mountain ridges, sag-ponds, dislocated ridges, etc. exist along the fault. Based on the analysis of field investigation and the data available, we believe that the surface rupture is due to a strong earthquake in the history of this area. And it is inferred that the Madoi- Gade fault within the Bayan Har block has been highly active since Late Quaternary and may still be active nowadays.