Abstract: To prepare a kind of high efficiency grouting superfine cement slurry with low viscosity, using superfine cement, water reducer and superfine fly ash as experimental materials, and the effects of water-cement ratio, fly ash and water reducer on the viscosity of the slurry, the strength of the stone body, bleeding rate and density are analyzed through using orthogonal test method and the experimental data were processed by SPSS software. Finally, the optimum proportion of the slurry is obtained. The results show that the water-cement ratio is the main factor affecting the assessment indexes; with the increasing of water reducing agent, there is no significant change in 28 d strength and density, but the viscosity keeps going down, the 7 d strength increases, and bleeding rate increases; with the increasing of quantity of ultrafine fly ash, the viscosity decreases and the 7 d strength increases, but the 28 d strength, bleeding rate and density are not significantly affected; when the water-cement ratio, water reducing agent and replacement level of superfine fly ash are 1∶1, 0.25%, 25% respectively, the slurry is the best proportion.