Abstract: In order to solve the safety problems of roof collapse and fracture water diversion brought by overlying high-confined sandstone aquifer, coal seam 3-1 and roof of Bayangaoler mine in southern Ordos basin. taken as the research object. Based on mine geology, hydrogeological conditions, mining technology conditions and the characteristics of mine pressure, the development characteristics of roof collapsed fractured zone of coal seam 3-1 were analyzed and studied by combining the field pressure test and numerical simulation. The results show that the numerical simulation results are basically consistent with the field pressure test results. Finally, it is judged that after mining seam 3-1, the height of roof collapsed zone was 38.7 m, the maximum height of roof collapsed fractured zone was 126 m, and the ratio of fractured zone and mining height was 23.7. The results are basically similar to the experimental and measured values, which provide a new method for coal mine to predict the height of roof fractured zone. The research results provide a test method and reference for the safe mining in Hujirt mining area and other mining areas with similar geological conditions as well as the retention of coal pillars for roof protection and water separation.