The permeability coefficient is important to investigate permeability coefficient spatial distribution of groundwater flow. Based on Gardner model, the permeability coefficient vertical distribution model is established, expressed as exponential, which is controlled by saturation permeability coefficient, dimensionless depth and dimensionless flow rate. The model shows that the permeability coefficient vertical distribution for homogeneous typical soils is influenced by the difference between flow rate and aturation permeability coefficient. And then, simplifies the model is simplified as linear model based on Taylor's series and permeability coefficient of groundwater level and the earth's surface as control conditions. The error of linear model with the method of Taylor's series increases when dimensionless depth increases. The calculation results of the simplified model and the original model are compared. The result shows that the linear model with the method of permeability coefficient of groundwater level and the earth's surface as control conditions is more accurate than the linear model with the method of Taylor's series.