Based on correlation of horizontal dislocation with the length of betrunked gulch, it is proposed that the active Ertai Fault had ruptured 5 times since Holocene. The earthquake of M=8 took place during every stick-slip fracturing. Paleoseismic recurrence period was approximately 1800 yrs. We have estimated that the Ertai Fault will rupture again in the 3700 A. D. The earthquake will occur on the southern end of the active fault. This estimation is suppored by severed evidences, such as the surface of multi-seismic fault, multible cliff of displacement, seismic colluvial deposits and excavation.