Abstract: In order to reduce the cost of filling，the relationship between the exposure height of filling body and intensity was calculated out by the empirical formula based on the analysis of mechanical mechanism of high-level subsequent filling body，and the design basis of filling slurry ratio was concluded. Then，the ultra-fine full tailings and the self-developed slag cementitious materials were mixed to prepare the backfilling slurry. By the way of orthogonal design and range analysis，the study focused on the relationship of the slurry above with various influencing factor，obtaining the weight of each factor and the optimal filling ratio. The results showed that the high-level subsequent filling body's strength must pass 2.9 MPa in the exposure level at 95 m，and 3.1 MPa in the exposure level at 100 m. Choosing the slurry with lime-sand ratio of 1∶5 and the concentration of 72% as cementing surface，the slurry with lime-sand of 1∶10 and the concentration of 72% as filling body can completely meet the requirement of the stope stability.

Key words: Slag cementitious materials, Strength, Stability, Regression analysis