Coal mining has produced a large number of shallow cracks (“downward cracks”), which cause water and soil loss and ecological degradation. Coal mining has a huge impact on the ecological environment. This phenomenon is further aggravated by the superimposed mining of multiple coal seams. This study takes the two geomorphic conditions of wind beach and loess ridge as the research background. Based on the selection of typical working faces, the development law of downward fractures in multi coal seam superimposed mining has been studied by means of field geological survey, statistical analysis, numerical simulation and borehole logging. The results show that the downward cracks development laws of wind beach landform and loess landform are different when a single coal seam is mined. The depth and width of downward cracks produced by coal mining in wind beach landform are smaller, the cracks spacing is more stable, and there is no hidden cracks development. As the downward cracks of coal mining under the loess landform is more complex, the development law of downward fissure of multi coal seam superimposed mining under the loess landform has been further studied. There is no significant change in surface cracks in multi seam superimposed mining compared with single seam mining, but the density of hidden cracks is higher in multi seam superimposed mining. After the superimposed mining of coal, the density of hidden cracks increased by 100%, and the average height of hidden cracks increased by 60.95%. The research results provide key parameters for the treatment of multi seam superimposed mining subsidence areas under different geomorphic conditions.