Located in the Eastern Tianshan-Xingmon geosynclinals system,the main body of the Xar Moron River fault zone is a WE-striking large-sized faulted structure extending along the Xar Moron River,and is also one of the larger faulted zones in Northeast China.The position of the fault has always been a hot topic in geological history.Now the research on the fault zone is mainly concentrated on the west region of the Da Hinggan Mountains,whereas the research on the east of the region is relatively insufficient.The authors analyzed the gravity magnetic and MT characteristics of the Xar Moron River fault in the east region of the Da Hinggan Mountains,separated the gravity magnetic fields by wavelet multi-scale analysis method,and inferred the location of the Xar Moron River fault.According to the images obtained that include the abnormal information and MT profile,the authors hold that the Xar Moron River fault is an ultracrustal deep fault.