Abstract: In order to study on the effect of brine on the strength of tailings cemented backfill, the strength test of fillings under different curing ages, different mixing waters and different sand-sand ratios is carried out.The test results show that the strength of the filling block and the maintenance age are a power function relationship.Brine will increase the early strength of the filling(7 d), but will reduce the long-term strength of the filling(7-28 d).Through the analysis of the extremely poor influencing factors of the filling body strength, the curing age is the main factor affecting the strength of the filling body.