Mine slag activity excitation mechanism was studied and analyzed, through the contrast experiment, gypsum and clinker stimulating the activity of slag was studied under the action of alkaline admixture, one new backfilling cementing material was developed, and compared with P.O42.5 and P.S.A32.5 cement intensity. The experimental results showed that under the effect of 5% alkaline admixture, Gypsum content was 20%, when the clinker content was 15%, the slag could be stimulated to the greatest degree of activity, the technology could improve the strength of filling body, play an important role on the development of filling mining.