Abstract: Taking into account the effect of blasting crushing and the stability of filling body in the subsequent two-step mining of filling stope is of great significance for efficient and safe mining of mines. The dynamic parameters of ore and backfill were obtained through the Split Hopkinson Pressure Bar （SHPB） test. Based on these properties， the finite element software ANSYS/LS-DYNA was used to simulate the blasting effect and backfill response of various solutions such as different hole bottom distances， row spacings and protective layer thicknesses of backfill. According to the on-site blasting monitoring data on Jinding Iron Mine in Shandong Province， the Sadovsky formula of particle vibration velocity was fitted， and combined with the numerical simulation results， the feasibility of applying numerical simulation was analyzed. The results show that: ① The dynamic compressive strength of 50.3% grade magnetite is 53.8 MPa， the dynamic elastic modulus is 21.6 GPa， the dynamic tensile strength is 11.7 MPa， and the average dynamic compressive strength of filling body is about 6.19 MPa.② Numerical simulation of blasting effect shows that the blasting scheme of hole bottom distance of 2.9~ 3.1 m， row spacing of 1.8 m， and protective layer thickness of 1.5 m or more can efficiently use the explosives and get the best blasting effect. And the maximum vibration speed of the filling body is less than 12 cm/s， which meets the requirements of blasting safety regulations， and can ensure backfill stability.③ The result of the fitting formula is consistent with the numerical simulation result， which proves that ANSYS/LS-DYNA software can be used to study the blasting effect.

Key words: underground mining, Split Hopkinson Pressure Bar （SHPB） test, dynamic mechanical properties, blasting effect, ANSYS/LS-DYNA, stability of backfill