Abstract: Slurry is a kind of widely-used engineering fluid. Slurry will seeps into the formation in the process of construction, which has a certain impact on the project. In order to make deeper study on the seepage mechanism of slurry, the formation is simulated as porous medium, the slurry is simulated as Hershel-Bulkley fluid which can more comprehensively reflect its rheological properties, and the seepage model of Hershel-Bulkley fluid in porous medium was established based on Fractal theory. Based on the calculation results of seepage model, the effect of pressure gradient, flow index, consistency coefficient and porosity on the instantaneous average velocity of Hershel-Bulkley fluid in porous medium were analyzed in detail. It is pointed out that the change of velocity has a power exponential relation with the change of pressure gradient, flow index and consistency coefficient, and a binomial relation with the change of porosity. The results provide theory basics for design and construction of slurry grouting in relevant projects.