Small coal pillar roadway protection is an important regional anti-impact technical measure, but the gob-side entry is prone to problems such as coal pillar fracture development, air leakage and water diversion, which in turn leads to multiple disaster risks such as goaf water damage, coal seam spontaneous combustion and toxic and harmful gas emission, seriously threatening the safe production of the working face.In view of the lack of quantitative determination method of grouting time and pressure threshold, this paper takes the gob-side entry of small coal pillar in Hongqingliang Coal Mine as the research object. Through theoretical analysis and numerical simulation method, the influencing factors of fracture development of small coal pillar are identified, the optimal selection of grouting time and pressure threshold of small coal pillar is discussed, and the synergistic control scheme of small coal pillar modification is put forward.Based on the modified Burgers theoretical model, it is found that the main factors affecting the fracture development of coal pillar are the viscosity coefficient ηK of Kelvin body and the elastic modulus EK of Kelvin body. The small coal pillar enters a relatively long plastic stage at about 38 meters behind the heading face. It takes about 10.5 days for the fracture network of coal pillar to reach a relatively stable development state, and the corresponding heading face distance is about 52.5 meters.The numerical simulation shows that the plastic stable distance is concentrated in the range of 30 ~ 60 meters, which further demonstrates the rationality of the theoretical research.At the same time, it is found that the overall pattern of coal pillar stress and plastic zone distribution has been basically formed in the early stage of excavation. Only with the advance of distance, the range of stress and plastic zone expands slowly until it enters a stable state.Based on this, a filling and plugging scheme with staggered arrangement of low temperature reinforcement materials and plastic plugging materials as the core is proposed.