Abstract: In order to prevent safety issues such as coal spontaneous combustion in abandoned tunnels of Mengcun Mine, we has decided in the mining area to use the method of underground excavation gangue to fill roadway in stages for fluidized filling of abandoned roadway.While dealing with coal gangue in a large scale, abandoned roadways are sealed to achieve the purpose of filling and disaster reduction.In order to ensure the filling effect, reduce the filling cost, and improve the filling effect, this article conducts a study on the proportion of gangue fluidized filling slurry.Through the grading analysis of gangue from Mengcun Mine, the influence of concentration, fly ash content, and water reducing agent content on the rheological characteristics of the gangue fluidized slurry is studied, and the optimal combination of gangue content, gangue particle size range, and admixture content is determined, A filling slurry formula with a concentration of 78% suitable for long-distance pipeline transportation in Mengcun Mine has been developed.This formula through increasing coal gangue content and slurry concentration, enhances solid waste treatment capacity, reduces the use of additives, and saves filling costs.