Abstract: In order to study the water-inrush disaster law of collapse column under the influence of interstitial material activation, a return air roadway of Shenhua Group was taken as the research object. The strength reduction and permeability mutation caused by rock destruction inside and outside collapse column and activation and loss of fillings were considered. FLAC3D simulation was used to study the characteristics of displacement, permeability coefficient, pore water pressure and water inflow of collapse column and surrounding rock in the process of roadway excavation. On this basis, the influence of fillings packed height of collapse column on water inrush was analyzed. The results show that: with the increase of the distance between roadway and collapse column fillings layer, the width and depth of the activated loss of collapse column fillings in the roadway floor will be larger and larger, resulting in the rock displacement between collapse column water-conducting layer and roadway bottom is increasing and the overall slip trend appears. Finally, when the roadway driving face exceeds 1 m of the collapse column central axis, the high-pressure water of the collapse column injects water into the roadway through the activation and loss channel of fillings. And the water inrush has the characteristics of large volume, suddenness and hysteresis. The larger the fillings packed height of collapse column is, the later the water inrush time node of collapse column relative to roadway excavation surface is. However, when the fillings packed height of collapse column reaches 22 m, water inrush will not occur in the collapse column.