Abstract: Combined with the fully mechanized mining principle of backfilling with solid materials, this paper analyzes the relationship between equivalence mining height and compacted rate of filling body. According to the engineering geological condition of a coal mine, the effect laws of compacted rate and mining height of backfilling materials on surface subsidence are analyzed by using numerical calculation software FLAC^2D .The results show that the value of surface subsidence is larger and the subsidence coefficents are 0.687 and 0.583 respectively when the compacted rate of backfilling materials are 50% and 60% , and the value of surface subsidence has an obvious decrease when the compacted rate is 75% and 90%. The peak value of surface subsidence increaes with the increase of mining height, which shows the linear rule.