Abstract: In view of the problems such as difficult to determine the reasonable size of coal pillar and support in gob side entry with composite roof, Taking the working face with one face and three roadways in 3-1 coal seam of Bojiang Haizi mine as the engineering background, the distribution law of coal pillar stress after mining is studied by using the methods of theoretical analysis and field measurement. The field measurement results show that the stress of coal pillar can be divided into low stress area and high stress area along the lateral direction, the distance between the low stress area and the edge of the goaf is 14m, and the distance between the high stress area and the edge of the goaf is 14-22m, the peak stress is 29Mpa, considering the development of coal seam fissures, coal wall spalling and other factors, the width of coal pillar in gob side entry driving is determined as 9m. At the same time, combined with the specific geological conditions, the gob side entry support scheme design and mine pressure observation are carried out. The roadway support practice shows that after the determined coal pillar width and anchor cable mesh support parameters are adopted in the test roadway, the surrounding rock of the roadway is stable, and the safe and efficient mining of the working face is realized.