At 23∶59′, December 18, 2023, a Ms6. 2- magnitude earthquake occurred in Jishishan County, Gansu Province. The major axis of the extreme earthquake was in the direction of NNW, with a maximum intensity of Ⅷ and a maximum ground acceleration of 1. 0 g. About 15×104 m2 of liquefaction collapse occurred on the headwater platform of Dashagou basin, Zhongchuan Township, Minhe County, Qinghai Province, 20 km from the epicenter. The active water and soil volume was about 60×104 m3, and about 45×104 m3 of soil side flow entered the gully, impacting the gully from north to south to form a disaster chain, and accumulated about 30×104 m3 in Caotan—Jintian Village, resulting in 20 fatalities.Objectives: The study of liquefaction and lateral flow of seismic sand is not only a scientific problem related to the formation mechanism of geological disasters, but also a realistic problem that must be faced in formulating practical disaster prevention and reduction countermeasures. This study is to clarify the formation factors, dynamic mechanism and movement characteristics of soil flow disaster chain, and provide a basis for preventing and coping with similar geological disasters.Methods: By using the methods of field investigation, interview, satellite remote sensing and UAV image interpretation, water content measurement, analysis and description, and calculation, the author has carried out the zoning of the soil flow disaster chain in Dashagou basin, and tried to obtain the scientific understanding combining qualitative and quantitative.Results: The distribution length of the disaster chain of soil flow in Dashagou basinis about 3. 1 km, which can be divided into five parts: soil liquefaction loss area, soil flow obstructing and returning silt area, roadbed blocking impact area, soil overpiling and buried area, and mud flood area. From upstream to downstream, it causes damage to cultivated land, collapse of electric tower, destruction of irrigation channel, destruction of village road, burying of township road, burying of personnel house, and silting of Yellow River diversion irrigation channel. The soil flow has a transitional ternary layered structure, including the ice water layer at the bottom, the mud flow layer in the middle and the wet soil layer at the top. The movement time from the start of the liquefaction soil to the buried pressure of Caotan—Jintian Village was less than 10 min, the time from the start of the soil flow to the roadbed collapse of Meiyi Village was about 4. 38 min, and the time from the arrival of Caotan—Jintian Village was about 6. 15 min, resulting in the Caotan—Jintian Village disaster within the following 3. 5 min.Conclutions: The formation of the disaster chain of soil flow in Dashagou basin is both inevitable and accidental. It is a rare geological disaster chain that includes the damaged land in the starting area, the electric tower, the roadbed blocking in the circulation area, and the sedimental area——The dwellings and irrigation channels in Caotan—Jintian Village. The formation of soil- flow disaster chain is the result of the overlapping of many factors such as geology, water source, dynamics, topography and disaster bearing bodies, including thick silty soil, high groundwater, strong ground motion, gentle terrain inclined to gully outlet, roadbed blocking energy storage outburst and multiple disaster bearing bodies along the way. The dynamic effects of soil flow in the gentle channel include soil liquefaction in the starting area, gate beam flow in the channel, subgrade collapse across the channel, ice water lubrication in the channel, water and soil train accumulation in the village and earthquake stress and panic of the victims. The village dwellings were built on the alluvial beach of Dashagou baisin, which virtually increased the risk of disaster and the difficulty of independent prevention.Countermeasures: Some suggestions are put out in this paper that consists of to carry out disaster prevention and mitigation training, prevent the risk of geological disasters, change farmland irrigation to drip irrigation, urban and rural communities to build sites to avoid flood plain or floodplain, dredging rivers to widen the cross section, soil flow initiation area to carry out land readjustment and soil and water conservation.