Abstract: Taking Daizhuang Coal Mine coal gangue paste backfilling as example, phy-chemical properties and optimized proportion experiment of gangue, fly ash and other materials are studied. The study result shows that the particle distribution of second-class crushing gangue is met the requirements basically, the particle of fly ash is more coarse and something like sphere glass pearl is less, and the lubricated effect on pipe is ordinary. The proportion experiment shows that P10 is the most optimized proportion result of the experiment, the proportion of cementing material, fly ash, and coal gangue is 1:4:6, the quantity concentration is 74%.