Abstract: By use of conventional triaxial compression tests, changing trends of the secant modulus, volume deformation, peak strain and the ratio of modulus to strength of the plastic concrete are obtained from changed bentonite and cement mixing ratios (0.93, 0.50, 0.35, 0.26). The analysis results show that the peak strain and the maximum volume compression drop significantly with the decrease of the bentomite and cement mixing ratio, namely the crack resistance and ductility of the material are significantly decreased. The impacts of the bentonite and cement mixing ratios on the ratio of modulus to strength are not very remarkable. When the bentonite and cement ratios of the plastic concrete are 0.93 or 0.50, the ratios of modulus to strength are first increased and then decreased with increase of the confining pressure. But when the betonite and cement ratios are 0.35 or 0.26, the ratios of modulus to strength decrease gradually with increase of the confining pressure. Finally, according to the research results of the triaxial tests, the analysis of parameters of the constitutive model for the plastic concrete conforming with the Duncan-Chang constitutive model has been made in the testing.