At present, ordinary Portland cement slurry is the common grouting reinforcement material in water conservancy engineering. In view of its poor fluidity, high drainage rate, low stone rate as well as its low strength and poor permeability performance problems, based on the preparation of different mixing ratios of cement-based expanded composite slurry, we adopted the single factor controlling variable method and the orthogonal experiment method to test the viscosity, density and mechanical performance of stone body. The experiment results reflect that adding fly ash could increase the workability and fluidity of slurry, and the bentonite could improve the stone rate of grouting and slurry stability. At the same time, bentonite also could reduce the drainage rate and slurry fluidity. The slurry mixed with bentonite and fly ash got improvement with its fluidity and stone rate, but the stone body strength was poor in the early stage. In the later stage, its strength was mainly supplemented by the hydration of fly ash. Cement slurry mixed with appropriate expansion agent had a great influence on the expansion of the stone body and could also improve the anti-permeability of the stone body. Consequently, reasonable selection and control of fly ash, bentonite and expansive agent can obviously improve the grouting effect.