Abstract: Coal gangue slurry filling and disposal of solid waste is a new coal green mining technology that conforms to the green and sustainable development of coal mines and responds to national environmental protection policies.In order to establish the basic theoretical system of slurry filling, this paper uses the methods of theoretical analysis, simulation experiment and field industrial test to reveal the law of overburden movement in slurry filling space and master the distribution characteristics of voids available for slurry filling, Clarify the function relationship of "gangue slurry goaf gap".The research shows that the "key layer of slurry filling" is the key to control the space range of slurry filling in the mining process, and the spatial evolution process of "arch beam shell" corresponds to the free accumulation area, load influence area and compaction area of slurry filling space, which directly determines the effect of gangue slurry; The porosity of the collapsed rock mass in the goaf varies along the strike and vertical direction, which satisfies the negative logarithmic function relationship.Based on this, the spatial void distribution model of slurry filling is established, and the key areas of slurry filling are pointed out; Through the ground in-situ grouting filling test, the filling characteristics of gangue slurry in goaf space are proved, and the action process of gangue slurry-gob gap has experienced three stages: initial flow, inrush flow and horizontal diffusion.The industrial practice of gangue slurry filling in the free accumulation area and load affected area of slurry filling space in Huangling No.2 well has successfully verified the feasibility of underground gangue slurry filling technology and the correctness of theory, which provides a new basis for gangue solid waste disposal and green mining.