In this paper, starting with palaeoearthquakes and historic and recent earthquakes recurrence intervals for main active fault zones in middle-eastern segment of Qilian Mt. since Holocene, by calculating the ratios of recurrence interval of strong earthquake to that of average(T/T_a), the strong earthquake recurrence probability model is established, and the model has applied to predict possibility and sites of strong earthquake. It reveals that, in this rigion the possible site where strong earthquake maybe occurs in future is on Maomaoshan-Jinqiang segment of Laohushan-Maomaoshan Fault.