Abstract: To solve the problem of coal roadway deformation in soft rock roadway affected by dynamic pressure influence in Chahasu Coal Mine, combined the theories and computer numerical simulation, we analyzed the floor heave and spalling mechanism under the influence of multiple minin, calculated a rational pillar size and designed bolt-cable coupling improvement support projects in No.31 mining area on the basis of the original support plan. The study result shows that it was expansion-flexural composite of floor heave and rib spalling affected by coal pillar size. It can effectively control the volume expansion of floor heave at the roadway bottom and reduce the impact of the surrounding rock pressure of two sides on the floor by increasing coal pillar size to 25 m and using "add floor rock bolt and increase support density in two sides of roadway and enlarge anchor length" comprehensive reinforced support means.