Abstract: In order to solve problems of big roof pressure and hydraulic support crushed down on working face during lower coal seam mining, taking Hanjiawan Coal Mine as engineering background, stress evolution law and roof movement law before and after blasting of residual coal pillar were studied by UDEC simulation software from the viewpoint of interaction of coal pillars. The study results show that the upper pillar blasting before the lower coal seam mining can effectively eliminate the stress concentration of the surrounding rock; vertical stress of roof reaches the maximum and is easy to appear support crushed caused by load concentration when long wall working face locates directly below coal pillars. The study result has a certain guiding significance for roof control of mine safety mining in similar condition.