Abstract: The cement-based grout is widely used in underground construction, mining engineering, and control of water disaster and so on and it is always used to block and strengthen. Ultrafine fly ash is conducive to strengthen the mobility of cement-based grout, so we take the way of using ultrafine fly ash to replace cement in cement-based grout. Changing the water cement ratio, cement content and water glass in volume, we study the viscosity, bleeding of an hour, stone rate and compressive strength of 28 days and the relationship between them, and then use the origin to deal with the experimental results and obtain the empirical equation between each element and the experimental results. The experimental results and empirical equation show that a definite relational model existing in parameters of cement-based grout and water cement ratio, cement content and water glass in volume.