Abstract: Fully mechanized coal mining and backfilling with solid waste，such as waste rock，fly ash，and loess，creates advantages for effective mining of coal under buildings，railroads，and water bodies．According to field geological conditions and the equal mining height concept，we analyzed the effect law of the equal mining height arose from different bulk factors of backfilling bodies．Moreover，we numerically simulated the strata movement and surface subsidence control under the condition of different bulk factors，and put forward that the allowable bulk factor of backfilling body is 15% based on allowable ground subsidence．Finally，the engineering application confirmed that the strata movement controlling is effective，and the surface buildings and facilities are not severely influenced．The research results has provided references for the effective execution of fully mechanized coal mining with solid waste backfilling．

Key words: backfilling body, bulk factor, strata movement, equal mining thickness, numerical simulation