Abstract: Taking filling mining of a metal mine as the study background,the compressive and tensile strength tests of backfill body under different proportion parameters were carried out,and the strength evolution characteristics of backfill under different proportion parameters were analyzed. Meanwhile,FLAC3D numerical simulation software was used to analyze the mechanical characteristics of filling body and surrounding rock in the process of orebody mining and goaf filling,revealing the mechanical effect of filling body in the stope. The results show that with the increase of curing time,the mechanical strength of backfill tends to increase continuously,and the compressive strength of backfill with higher concentration or cement-sand ratio increases more. At the early curing stage,the influence of cement content reduction on the strength of cemented tailings backfill is not significant. After orebody mining,the roof and floor of stope show the characteristics of compressive stress concentration, but the stress concentration of surrounding rock is obviously improved after goaf filling. In addition,after the second-step goaf filling,the tensile stress value of the filling body reaches 0. 20 MPa,which exceeds the tensile strength of some backfill. Therefore,it is recommended that the lowest ratio of cement to sand of the backfill should be 1 ∶ 6 to maintain the stability of the backfill in the stope.