Abstract: For extremely thick coal seam of dozens of meters，even hundreds of meters，roadways are all located in coal seam.Due to its looseness and brokenness，and without stable anchoring base in deep coal seam，the anchoring force was greatly reduced.Regarding to the complex geological conditions of East Junggar full seam gateway in Xinjiang， a numerical simulation was conducted by using the finite difference software FLAC^3D and in combination with the rock mechanical tests at laboratory，to simulate the grouting effects.The results indicated that grouting in loose and broken coal seam has a good reinforcement effect on coal seam，and improves the mechanical parameters of surrounding coal seam to promote anchoring performance and prevent further development of plastic zone and control the deformation of the surrounding rock.The range of grouting diffusion in coal and rock fracture is defined as the equivalent grouting layer and six different grouting diffusion radius of 1.0,1.5,2.0,2.5,3.0,4.0 m are simulated respectively.By comparison，2.5 m is determined as the optimum grouting depth.This research is of great significance in guiding safe，economical and reasonable supporting of full seam gateway in extremely thick coal seam.

Key words: Full seam gateway, Anchoring performance, Grouting, Numerical simulation