Abstract: In order to improve the effect of filling method on controlling ground settlement，the theoretical analysis method was adopted to conclude that improving the backfill roof contact rate is the key factor for controlling the ground settlement.Then，in view of the present low roof contact rate，an improved expanding backfill method of replacing traditional cementations and tailings mixture with burnt lime was proposed and the expansion properties of expanding backfill was gained by the experiment.The experiment result showed that the expandable backfill can improve the roof contact rate of filling body and its expansion force can generate some support force on the roof rock.The expansion forces are 1.14 MPa，0.68 MPa and 0.47 MPa when the cement-sand ratios are 1∶1，1∶3 and 1∶5 respectively.Finally，based on the experiments，and taking -175 m stope of western district in Chengchao Iron Mine for instance，the effect of expanding backfills on controlling ground settlement was studied through numerical calculation.The calculation results and theoretical analysis are in good agreement.The calculation result shows that expanding backfill can lower the ground settlement by 94% in maximum.

Key words: Filling method, Ground settlement, Backfill roof contact rate, Burnt lime, Expansion force, FLAC^3D