Abstract: In view of the problems of land occupation and water and soil pollution caused by a large amount of coal gangue,combining with the actual conditions of Weiqiang Coal Mine,the coal gangue is considered to be crushed and screened as the basic aggregate for goaf grouting,so as to realize large-scale consumption of coal gangue.In this study,the fluidity differ ence between the slurry made from full-graded coal gangue slurry and the traditional loess slurry after particle size optimization and the flow effect of aggregate in the slurry with the slurry expansion were compared to explore whether the fluidity of the new coal gangue based slurry meets the requirements of grouting from two aspects.The results show that the particle size of tradi tional coal mine grouting loess material is mainly 20 mesh to 60 mesh (0.25 mm to 0.8 mm),accounting for 41%.After parti cle size optimization,the particle size distribution of crushed coal gangue is mainly 30 mesh to 50 mesh (0.3 mm to 0.6 mm), and the particle size distribution of the two materials is similar.The fluidity of slurry prepared by using 30 mesh to 50 mesh coal gangue powder as the basic aggregate and the solid-liquid ratio of 1∶2 is 70 cm,which is basically close to that of tradi tional loess slurry,and the flow effect of aggregate with slurry in the new coal gangue based slurry is better.It was found that the slurry fluidity of coal gangue increased with the increase of grinding mesh number below 50 mesh,and the slurry flow per formance decreased with the further increase of grinding mesh number.Based on the flow performance,the optimal particle size range of coal gangue to prepare goaf grouting materials was 30 mesh to 50 mesh (0.3 mm to 0.6 mm).The study results providesreferenceforpreparingnewcoal ganguegroutingmaterials inWeiqiangCoalMineandothermineswithsimilargrouting conditions.