Mineral admixtures are important part of cement-based grouting materials for semi-flexible pavement. The coordination of mineral admixtures plays an important role in improving the fluidity and mechanical properties of grouting materials. In this paper, blast furnace slag powder, cenosphere and silica fume were selected. The effects of the three mineral admixtures on the fluidity and mechanical properties of grouting materials for pavement were investigated by the orthogonal experimental design method, and the hydration product composition and morphology of hardened paste of grouting materials were analyzed by means of XRD and SEM. The results show that the order of influencing factors of the cooperative optimization of three mineral admixtures on the fluidity and mechanical properties of grouting materials is cenosphere, silica fume and blast furnace slag powder.Among them, cenosphere has the most significant effect on improving the fluidity of grouting materials, and silica fume and blast furnace slag powder have the obvious effect on promoting the mechanical properties of grouting materials. According to the evaluating indicator of the fluidity and early strength of grouting materials, the optimum content of cenosphere, silica fume, and blast furnace slag powder is 15.0%, 1.5% and 5.0% (both are mass fraction) respectively. In addition, the synergistic addition of three mineral admixtures has little effect on the composition and morphology of early hydration products of grouting materials. It shows that the improvement of early mechanical properties of grouting materials by three mineral admixtures is mainly caused by the improvement of hardened slurry materials compactness through physical filling.