Abstract: By analyzing the influence factor of permeability coefficient of broken rock in subsidence areas, we obtain that the permeability coefficient is depended on the distribution parameter and size of maximum broken rock. Through matching small broken rock samples from different particle sizes distribution subsidence and determining the coefficient of permeability, we establish the relation between permeability coefficient and maximum particle diameter and particle size distribution parameters. Example calculation shows that just make sure the size distribution parameter of the subsidence and broken rock and the maximum particle diameter, we can more accurately calculate the broken rock permeability coefficient of the subsidence according to the relationship equation.