Abstract: To explore a systematic key technical system for nonpillar mining with automatically formed entry by roof cutting and pressure release under different coal thickness conditions, a thin coal seam mining face of Hecaogou No.2 coal mine, a medium-thick coal seam mining face of Dianping Coal Mine and a thick coal seam mining face of Ningtiaota Coal Mine were taken as the engineering background, the key design parameters of roof cutting and roof support were studied and on-site engineering tests were carried out. The research showed that the effects of roof cutting and roof support are the key to ensure successful implementation of the new technique. The key technologies can be summarized as the directional roof cutting technology, NPR constant resistance anchor cable support technology, temporary support technology in dynamic pressure area and gangue prevention technology. Under different coal thickness conditions, the movement state of the gangue in the gob area and the movement laws of the roof overburden were different, which determines that different technical parameters should be adopted.