Abstract: Coal pillar floor stress transfer law was researched by half plane body theory of elastic-plastic mechanics, and coal pillar floor stress transfer mechanics model is established. Combined with stress superposition principle, we get the calculation formula of coal pillar floor stress distribution, and coal pillar floor horizontal stress and vertical stress cloud was got by using MathCAD. Datong Mining Area Jurassic coal was selected as an example, different types of coal pillar horizontal stress and vertical stress distribution characteristics were analyzed. The stress magnitude and scope of vertical stress of coal pillar is the biggest, which played a leading role in the process of stress transfer. The depth of vertical stress concentration area of boundary pillar is the biggest, the depth of large section coal pillar (20 m) was the second, and the depth of small section coal pillar (10 m) was the last. Different arrangement of floor vertical stress of coal pillar was analyzed, and the overlap arrangement of coal pillar makes the depth and scope of floor stress higher. The mining of Jurassic coal group in Datong Mining Area was selected as an example, comprehensive overlapping action of coal pillar makes stress of 3-5^# coal seam from 12.4 MPa to 17.3 MPa, vertical stress are increased from 1.3 MPa to 6.2 MPa under the condition of no pillar. In the area of 125 m to 280 m, the vertical stress increased obviously, we suggest that the arrangement of mining roadway at 3-5^# coal seam working face should avoid this area.