Abstract: The medium-coarse sand has good physical and mechanical properties and extensive engineering applications. In order to further study on medium-coarse sand permeability and permeability deformation, statistical analysis on the type and parameter of permeability deformation is carried out base on the testing data of 48 samples taken from 6 projects. The results indicate that the permeability deformation types of all the samples are soil flow with the critical gradient value of 0.6~1.2,failure gradient 0.9~1.7, and permeability coefficient 2.010-2cms-1~2.010-4cms-1,meanwhile, the critical gradient and failture gradient have good correlativity.