Abstract: The particle composition of coarse-grained soil is complex, and it is difficult to accurately measure its permeability coefficient in practical projects, so it is particularly important to explore its empirical calculation formula. In this paper, through the particle gradation and permeability test of typical medium sandy soil in Yinchuan Plains, the influence of sand content on sediment permeability under the condition of particle grading is studied, and the correlation between permeability coefficient and gradation parameters is discussed. The empirical formula is revised. The results show that: when the sand content is more than 60%, the permeability coefficient increases linearly with the increase in sand contents; the permeability coefficient of coarse-grained soil is highly correlated with the non-uniformity coefficient Cu, R2 is 0.81; the empirical formula after introducing the non-uniformity coefficient Cu can better reflect the permeability coefficient and characteristic particle size of coarse-grained soil in Yinchuan Plains.