Firstly

the 6-parameter common finite layer method is proposed based on the basic principle of conventional method. The displacement mode of a layer element is taken in the product form of five complete polynomial and double series. By applying the static equilibrium equations of elastic medium to the layer element

the correlation rules among three-dimensional displacement polynomial coefficients are discovered. Thus six unknown and independent displacement parameters can be obtained

whose number is the same as nodal surface displacement with the result that completeness requirement for the displacement mode can be ensured. Secondly

the 6-paramter super finite layer method has been deduced by transforming operational matrix between the super finite layer element and its interior small elements

in which the coordination of higher order deformations between adjacent small layer elements can be satisfied. At last

it is concluded that the 6parameter common finite layer method is suitable for thin layered ground

while the super finite layer method is for layered ground with various thickness.