Abstract: In view of theoretical analysis and numerical simulation, the distribution characteristics of stress field, displacement field and plastic zone in the middle lane affected by mining are studied. The distribution law of plastic zone, stress field and displacement response of roof and floor in middle lane and working face under different steps are analyzed. The results show that the abutment pressure of coal and rock mass around the middle lane is inversely proportional to the width of the coal mass between the gob-side lane and the middle lane, and it varies with the angle between the middle lane and the gob-side lane. The deformation of roof and floor is the smallest when the middle lane is 45 degrees, and the peak stress concentration factor is the smallest when the lane is 135 degrees. The results of simulated plastic zone show that shear failure is the main failure mode of solid coal in working face, while tensile failure mode of coal pillar is the main failure mode. The volume of plastic zone in two different states is the smallest at 150 degrees, but it is not much different from 135 degrees. Comprehensive analysis shows that the optimum angle of middle lane is 135 degrees