During mining method for short distance coal seam group development, the lower coal was returned to mining roadway to make it affected by the coal seam mining, the remaining coal pillar in the vacant area and dynamic pressure of adjacent working face of coal seam. Combined with occurrence of roof and floor heave in No.14505 working side, analysis methods of field measurement, theoretical research and numerical simulation were used. The results showed that if vacancy on coal seam mining area of coal column width was small, the legacy of the lower coal roadway at the right and adjacent coal seam working face of coal roadway protection cylinder was small, and the roadway was easily affected by mining after losing steady state. The coal pillar size was 25 m and coal pillar of retaining wall of coal mining vacancy area was 20 m, which could ensure stability of lower coal roadway after reinforcement of roadway support.