To solve the problem of reasonable ratio of cemented backfill material in unclassified tailings, the unclassified cement filling experiments, based on the two cement material which are ordinary portland cement and slag cement, were carried out. The matching laws based on different cement materials were summarized. Meanwhile, the orthogonal experiment and single experiment of different admixtures were also performed. The influence of different admixtures on strength of unclassified tailings cemented backfills was obtained. The study results show that it is unobvious cementation effect between the ordinary portland cement and the slag cement. With addition increasing, the cementation effect of ordinary portland cement is better than that of slag cement apparently. The amount of slag cement addition is suggested below 3%. Comparing the orthogonal experiment with single additive experiment, the strength is improved because of the additive 2 3 Na CO andKAl(SO4 )2 ·12H2O. They aren’t obvious effect for strength, such as 2 3 Na SiO , 2 4 Na SO and 4 CaSO .