Abstract: In view of the actual situation of 3213 fully mechanized working face in Xinjing Coal Mine, in the condition that the width of fillings beside the gob-side entry retaining in medium-thickness coal seam was 0.8 m, 1.0 m, 1.2 m, 1.5 m and 2.0 m respectively, the surrounding rock deformation was analyzed by means of numerical simulation. By checking the bearing capacity of the fillings, it was concluded that the reasonable width of the flexible-formwork concrete fillings was 1.2 m. During the retaining of roadway in 3213 fully mechanized working face, the basic supporting mode is "bolt" + "anchor cable" + "w-shaped steel belt" + "metal diamond mesh"; flexible-formwork concrete fillings with a width of 1.2 m was adopted to support the roadway, and anchors and steel strips were installed on the concrete; the temporary reinforced support adopted the method of "one beam and three columns", after the temporary reinforced support, two rows of anchor cables were constructed on both sides of the filling wall. The observation results show that the fillings beside roadway during the retaining remains are stable, the maximum deformation of the roof and floor of the surrounding rock and the two sides is 293 mm and 211 mm respectively, which meets the requirements for the use of the gob-side entry retaining.