Abstract: In order to research the mechanism and reasons of surface collapses in Qujiang Mine,based on the data of the temporal and spatial characteristics of su rface collapses,the results of geological exploration,the seasonal change law of annual precipitation,the record data of earthquakes and the conditions of coal mining in Qujiang Mine,the temporal and spatial relationship analysis between causes of nine surface collapses and several factors was carried out,including underground caves, precipitation,earthquakes and mining.The results showed that soil caves existed around surface collapses,the burial depth and relative distance mostly less than 20 m,s 0 the underground caves in shallow and thin cap rock were essential internal cause of surface collapses , and in March,the water level was minimum,the precipitation we re at most from April to June,occurring seven collapses,so the groundwater lowering and cap rock weakening in rainy season were direct external cause,moreover the i nterval time between occurring collapses and earthquakes was within 3 months,except No.1 surface collapse,so earthquakes were induced external cause finally,the Co rrelation between underground mining and surface collapses was not obvious, but the location of surface collapses was influenced by mining.