In order to promote the resource utilization of waste slag from stainless steel factory, the cementification materials were prepared with laterite nickel mine acid furnace slag and stainless steel slag as the main raw materials. The effects of mechanical activation and the mass addition amount of stainless steel slag on the properties of cementing materials were studied. The hydration products and microstructure of cementing materials were analyzed by XRD and SEM. The results show that mechanical activation is mainly through the changes of specific surface area and particle size distribution of raw materials to affect the properties of cementing materials, and the proportion of fine particles in blast furnace slag is the crucial factor affecting the cementing activity, the optimal ball milling time is 45 min, and the specific surface area of blast furnace slag is 524.66 m2/kg. There is a synergistic action between stainless steel slag and acidic slag. When the mass content of stainless steel slag is 20%, with curing ages of 3 d，7 d and 28 d, the compressive strength of mortar test block is 17.8 MPa, 24.3 MPa and 34.8 MPa, and the flexural strength is 4.5 MPa, 6.2 MPa and 6.8 MPa, respectively, which reaches the requirement of P·S 32.5R slag Portland cement strength standard. The addition of stainless steel slag facilitates the formation of ettringite and C-S-H gel at the early and late hydration stages, which increases the strength of mortar test block at various ages. The fine particles of steel slag without hydration also play a micro-aggregate filling role, which is conducive to the improvement of the early strength of cementing materials.