It is needed for dynamic nonlinear analysis of soil structures that to follows the history of the stress-strain and to evaluate the instantaneous tangential modulus of the stress-strain on hysteretic loop. Because the seismic loadings are arbitrariness

it is very complex that the trace of the stress-strain of the soil elements in the actual geotechnical engineering. It is different for this nonlinear analysis that is used the conventional expresses of the constitutive relationship of the soil dynamic behavior based on the skeleton curve and hysteretic loop. In this paper

the scaled memory (SM) model is introduced for dynamic nonlinear analysis of soil structures. The SM translates the nonlinear variation of tangential modules during monotonic loading into a piecewise linear distribution geometrical relationship

which can easily to be modified to simulate hysteretic characteristics of soil during cyclic loadings

it also can simulate the dynamic stress-strain response of arbitrary cyclic loadings. In order to determine the parameters of the SM model. An analysis program of nonlinear least square method is developed. The parameters of the SM model

such as

are defined by fitting test results. To compare the dynamic stress-strain relationships between the tests and the calculated results by SM model

it is shown that the SM model is capable and practicable.