Abstract: Through a series of large triaxial compression tests, the strength and deformation characteristics as well as the critical state of rock fill are investigated. The test results show that subjected to shear, rock fill samples under some state will exhibit shearing dilatation and strain softening behaviors, and that whether they will happen or not depends on its current state, which is characterized by both its density and effective mean normal stress applied. Under large strain levels, the critical state will appear in all the soil samples tested, and the critical state is independent of its initial state. In the plane, the critical state line of rock fill shows nonlinear characteristics.