To study and explore the influences of cement to sand ratio,the dosage of fly ash and slurry concentration on backfill quality,the orthogonal tests and variance analysis were carried out using the strength of backfill,bleeding rate and fluidity as the indexes and selecting orthogonal array L25(56).The results showed that for the three factors,the influence of cement to sand ratio on backfill quality is the largest,the second is the dosage of fly ash,the third is slurry concentration.The influence of water content on bleeding rate of backfill slurry is the largest,the second is cement to sand ratio,the third is the dosage of fly ash.The influence of water content on fluidity of backfill slurry is the largest,the second is the dosage of fly ash,the third is cement to sand ratio.