The north-edge fault zone of the Longshoushan fault is the relief boundary between the Chaoshui basin and the mountainous region of Longshoushan. According to the result of previous studies, three trenches have been studied in the Baijiazui trench at the eastern section of the fault, Baodiahe trench at the middle section and Xieposhan trench at the west, which reveal several e-vents to us. On the basis of comparative analysis of the three trenches, this paper shows that since Holocene, six events had occurred in the north-edge fault zone of the Longshoushan in the 11 ka; the average of the recurrence interval is about 1.57 ka. It is compatible with the predominance recurrence interval in other fault zones, which is 1~2 ka. (a) Some paleoearthquakes may be missed there as only two events occurred before 5 ka B. P and the recurrence interval was obviously more than 1~2 ka. (b) The activities of paleoearthquakes obviously clustered. The maximum of recurrence interval is 1.5 ka and the minimum is 0.7 ka, and the average is about 0.8 ka. All of these conclusions are close to maximum of recurrence interval of the historic earthquake (0.79 ka) in the Shandan-Zhangye region.