Abstract: 1115 (1) working area of 740m, which is based on the bridge, is studied in the background, and the reasonable width of the filling body is studied by theoretical analysis, numerical simulation and in-situ measurement. The results show that when the composite roof lithology is soft, the large area of the roof can be broken down and the large amount of subsidence is large. Therefore, the roof should be strengthened to maintain its integrity. At the same time, when the width of the filling body is about 2.5m, the stress and displacement of surrounding rock are optimized, and the successful application of this method in the actual production, so that the maximum shrinkage rate of the roadway is about 28.5%. meet the production requirements, indicating that the method is reasonable, and it has certain guiding significance to the practice of the gob-side entry retaining.