Active Zhongwei-Tongxin fault is a regional great fault belt located at the northern foot of Xiangshan Mountain. This fault is the east segment of large Tianzhu-Tongxin fault belt, its length is about 150km. The segment consists of a series of discontinuous faults. On October 14, 1709, a great earthquake(M=7.5) occurred on the segment in the south of Zhongwei. All strata singe the latg Epipleistocene cut by the fault, the offset is 25±3m the average slippins rate is 2.5mm/yr.. Since about 6000yrs. B. P. 3 great earthquakes (M≈7.5)have occurred on the fault. The average recurrence interval of the events 2299 yrs. The average recurrence interval obtained from the method of micro geomorphology is 2100 yrs.