To clarify the function mechanism of coal gangue (Mc) on geopolymer materials, geopolymer grouting material (CGGM) prepared from coal-based solid waste such as Mc was taken as the research object. The influence of Mc content and its particle size distribution on the rheological and mechanical properties of CGGM was systematically studied, and the microstructure of stone body was analyzed by microscopic testing methods such as MIP, XRD, FTIR, and SEM. The research results indicated that the stability of CGGM slurry was improved by Mc, its slurry was typical viscosity time-varying power-law type fluid, and the fluidity, setting time and compressive strength of CGGM decreased with the increase of coal gangue contents. When the mass fraction of coal gangue was 50% (precursor), compressive strength of stone body at 3 days and 28 days reached 2.97MPa and 8.89MPa, respectively. Mc mainly played the role of micro aggregate and provided nucleation sites for C-S-H gel in the early stage, and polymerization occurred in the later stage. Strength was mainly attributed to crystals and gels such as AFt, C-S-H, and C-(N)-A-S-H.