Abstract: The support pressure distribution law of the coal pillars under goaf in "two hard" and thin coal seam was studied through the UDEC numerical simulation. Results showed that lateral support pressure of the working face under the coal pillar of goaf in "two hard" and thin coal seam reached 16.1 MPa, and the filling body beside roadway needed to have a certain features that was "yield - resistance". Through the analysis of theoretical calculation and numerical simulation of FLAC^3D, parameters of filling body beside roadway were defined that the width of filling body beside roadway was 2.0 mPa, and the final strength was not less than 25 MPa. Through the deformation monitoring of surrounding rocks in the 88105 working face transportation roadway, and results showed that this effect of gob-side entry-retaining was better off according to this parameter.