Abstract: In order to study the influences of gradation, density and stress state on the strength and deformation behaviors of the rockfill materials, some typical materials are selected for large triaxial shearing tests, so a series of laboratory tests are designed under the conditions of different gradations, densities and confining pressures by the large triaxial equipment. According to the experimental results, and by analyzing and comparing the stress-strain characteristics, we can get many important conclusions: firstly, the larger the grain size of samples, the more obvious the strain hardening and compression behaviors among the shearing process, and on the contrary, the smaller the grain size of samples, the more obvious the strain softening and dilatancy properties; secondly, the strength and deformation of the rockfill materials are related to the density and stress state, and the influence of the sample initial gradation is so large that it should be paid more attention to; the last but not the least, the intensity envelope of the rockfill materials changes by a power function relationship, and the rationality and validity is verified by analyzing test results and calculation results. The research results of this paper are the basis of further studies of the state-dependent dilatancy theory and state-dependent constitutive model of the rockfill materials.