To predict the grout spread in fractured rock mass,a two-dimensional Bingham grouting model was employed based on orthogonal fracture network and a cell-centered finite volume method was used for numerical analysis. The grout spread was numerically calculated under different grouting parameters. A grouting radius formula with a grout quantity formula was put forward with the consideration of those parameters. The study results indicates that the grouting pressure,the viscosity of grout,the shear strength of grout,the aperture of fracture and the roughness of fracture dominate the grouting radius,while the grouting pressure,drilling length and the aperture of fracture dominate the grout quantity. The formulas can be used to predict the grouting radius and the grout quantity under arbitrary parameters.