Abstract: In order to solve the problems of shortage of backfilling coarse tailings，serious segregation of filling slurry and low strength of the filling body in a copper mine at domestic，investigation on optimal matching scheme based on orthogonal experiment was carried out.In this experiment，such factors as filling slurry concentration，cement-aggregate ratio and fine tailings content are taken as the influencing factors and 28 d uniaxial compressive strength，filling slurry bleeding rate and filling slurry diffusion as the research indexes.The range and variance analysis is adopted to analyze the sensitivity and the significance of influencing factors to research indexes.Researches show that the factor of most sensitively affecting backfilling blocks' strength is cement-aggregate ratio，and that the factor of most sensitively affecting filling slurry bleeding rate and filling slurry diffusion is concentration；Cement-aggregate ratio significantly affects backfilling blocks' strength，and concentration and fine aggregate content both significantly affect the filling slurry bleeding rate while concentration affects it most significantly，and concentration significantly affects filling slurry diffusion.At last，the recommended matching scheme in this experiment was filling slurry concentration of 70% to 72%，cement-aggregate ratio of 1∶6 to 1∶8 and fine tailings content of 15% to 20%，and the optimal matching scheme of backfilling was filling slurry concentration of 72%，cement-aggregate ratio of 1∶6 and fine tailings content of 15%.

Key words: Backfilling ratio, Orthogonal experiment, Fine aggregate content, Scheme optimization