Abstract: In view of the problems posed by low pozzolanic activity and large water requirement of normal consistency in the direct light calcinating of electronic fluorine-containing sludge as cement admixture, this paper uses coal gangue as a supplementary silicon and aluminum source of electronic fluorine-containing sludge to mix electronic fluorine-containing sludge and coal gangue and then to prepare cement admixture by light calcinating. This paper studied the effect of cement admixture prepared by light calcinating electronic fluorine-containing mixed with sludge coal gangue on cement properties through strength activity index, mechanical properties of cement, water requirement of normal consistency, setting time, particle size, X-ray diffraction and scanning electron microscopy. The results show that compared with direct light calcinating of electronic fluorine-containing sludge to prepare cement admixture, light calcinating of electronic fluorine-containing sludge mixed with coal gangue can improve the particle gradation of cement and reduce the water requirement of normal consistency of cement. It can significantly improve the activity of cement admixture and the strength of ordinary portland cement. Significantly extending the initial setting time and shorten the final setting time of cement.