Solid waste utilization is one of the important ways to achieve the goal of “double carbon”. Taking solid waste CaF2 sludge as cement admixture, the effect of CaF2 sludge content on the properties of cement cementing material was investigated through compressive strength and slurry fluidity tests, and the mechanism was analyzed by XRD, SEM and TGA-DSC microscopic characterization tests. The results show that the addition of CaF2 sludge can improve the early strength of cement cementing material. The compressive strength of cement cementing material with 8% (mass fraction) CaF2 sludge is better. The addition of CaF2 sludge leads to the decrease of slurry fluidity, but the addition of less than 10% (mass fraction) has no significant effect on slurry fluidity, compared with the cement without CaF2 sludge, the slurry fluidity of the cement with 8% and 10% (mass fraction) CaF2 sludge is reduced by 3.0%. CaF2 sludge mainly plays a physical effect in cementing material, and CaF2 sludge can form more crystallization sites to promote cement hydration. The dilution effect and agglomeration effect of CaF2 sludge to cement increase significantly. The microscopic properties of cement with 8% (mass fraction) CaF2 sludge are better.