Abstract: The stability control of filling body is one of the key factors for the success of gob-side entry retaining. In order to obtain a reasonable filling body stability control technology, the paper took the No.7136 working face of Sanhejian Coal Mine as the engineering background, and used UDEC6.0 to correct the numerical modal of the filling body (water cement ratio of high water material was 1.5∶1.0). Then the diameter of reinforcing steel ladder beam and pulling anchor rod were controlled by filling body stability. The stress and strain of filling body with different diameters and quantity were simulated and analyzed. The results showed that the reinforcement effect of filling body can effectively restrain the surface displacement of filling body, comprehensively enhance the bearing capacity of filling body up to 20%, improve the stability of filling body along gob-side retaining roadway, especially increase the diameter and quantity of tension bolt under the condition of large deformation, which can effectively control the overall transverse of filling body side. Deformation and bulging is one of the important parameters to improve the surface protection capacity and bearing capacity of the filling reinforcement system. The research results have been successfully applied to the gob-side entry retaining in a kilometer deep well. The average deformation of the backfill wall after reinforcement was not more than 150 mm, and the roof subsidence was not more than 250 mm. It showed that the backfill reinforcement system was reliable and had good adaptability.