A general calculation formula for the average physical index’weighted processing is deduced according to the relationships among the different calculation amount, physical index and soil thickness for layered soil. The paper gives the expressions for the average index such as the average soil severe, average fiction resistance of pile sides, horizontal average permeability coefficients, equivalent value of the soil compression modulus, shear wave velocity of soils, average permeability coefficients in vertical dimension and the average proportion coefficients. This paper also analyzes the error size and changing rule of different calculation methods for the same physical index.