By analyzing the regional distribution of unconformity in Cenozoic strata and their sedimentary characteristics we found that there were at least two tectonic events affecting central-southern Ningxia during the Miocene, one in the Early Miocene, the other in the late Middle Miocene, and the later one was much stronger and more widespread than the former one. The former one was found to the west of the Liupan Mountain, and the later mainly occurred along the Chahanbulage-Sanguankou-Qingtongxia-Guyuan (Cha-Gu) fault. Most the Hongliugou Formation in central-northern Ningxia was deposited under stronger tectonism in the Miocene. The tectonic event in the early Miocene mainly distributed to the west of the Liupan Mountain including eastern Gansu, and this event resulted in the deformation of the Qingshuiying Formation and the unconformity between the Hongliugou Formation and Qingshuiying Formation. Because most of these phenomena were distributed along the Haiyuan fault and adjacent areas, we conjecture that the Haiyuan fault may be active in the early Miocene. And the event in late Middle Miocene had shown its existence in the following aspects, in the west of the southern Helan Mountain the thrusting taking place in the late Middle Miocene has been found, thick syntectonic sediments, Hongliugou Formation was deposited, the unconformity between the Hongliugou Formation and Qingshuiying Formation because of the tectonism in late Middle Miocene along the Cha-Gu fault was also found, the Hongliugou Formation in these areas also deposited at the same time, which means that during that time the deformation front of the Qinghai-Tibetan plateau had extended to the Cha-Gu fault, i.e. the western margin of the Ordos basin, the early Cenozoic basin was dismembered in this event; and at the same time the Hongliugou Formation in the basin became coarser and coarser upwards which also means that in the late Middle Miocene one stronger tectonic event had affected this region. This event led to the uplifting of the Xiang Mountain, which dismembered the former basin to small piggy-back basins. Undergoing these two tectonic events, central-southern Ningxia had been incorporated into the thrust wedge of the northeastern Qinghai-Tibetan plateau, and the reason for this thrust wedge extending to the northeast may be the remarkable uplifting of the northern part of Plateau at the same time which resulted in the taper angle of the wedge over the critical value and made it spread forwards. The Cha-Gu fault was once similar to the present Haiyuan fault as the deformation front, and the development of the whole of northeastern plateau was not forward-breaking, but expended with out-of-sequence. The above phenomena are not consistent with the viewpoint of former workers that the deformation of Cenozoic strata in Ningxia occurred since the end of the Pliocene.