Based on shallow coal seam passing through the valley terrain with dynamic load pressure disaster of Daliu Mine， numerical simulation model was set to study the reason. The result showed that the integrity of the overburden strata was the main reason to cause dynamic load pressure accident. When the main key strata is relatively complete， block each other can provide a horizontal force， which allows the block to form a relatively stable state of masonry beam structure， with normal mining pressure of working face.