The test results of large triaxial test and plane strain test for two kinds of coarse-grained soils are firstly described. Soil strain is assumed as two parts composed of elastic strain and dilatancy strain. The relationship of elastic strain and stress is supposed to obey generalized Hooke's law ； while the dilatancy strain obeys Rowe dilatancy law, and the elastic Poisson ' s ratio is assumed as constant. Based on these assumptions, the relationship between stress and three parameters including volumetric strain module Kp, dilatant module Kq , and shear module G is established, and a new nonlinear dilatancy model which is simple and practical with clear physical concept is preliminarily proposed. Subsequently, the collation method of the model parameters is given, and finally the mechanical significance of Poisson ' s ratio of the general nonlinear elastic model is demonstrated. The tests indicate that the model can well simulate the stress-strain curve for different coarse-grained materials. As for the same coarse-grained soils, the model parameters from the triaxial test and plane strain test are consistent except for the strength index. Model parameters for two kinds of coarse-grained soils are also offered.