Abstract: In order to get good flow property,high strength and reasonability of paste-like backfill material,proportion of backfilling material is studied by experiment.The result shows that in the range of experiment,strength of backfilling material varies linearly with content of sialite,and collapse height increases first and then decreases while content of fly ash increases.At the content 24% of fly ash,collapse height attains the most.The finally determined proportion makes the backfilling material technically feasible and economical.This article is of great importance to promote backfill mining.