A constitutive relationship for high strength concrete in triaxial monotonic and cyclic compressions is developed based on the continuum damage mechanics.The bounding surface concept is employed in the formulation of the theoretical model.An experimental program was undertaken in order to establish databases for high strength concrete under triaxial monotonic and cyclic compressions.The stress-strain responses of high strength concrete subjected to triaxial monotonic and cyclic compressions were acquired through an experimental program. Comparison of the stress strain results indicates good agreement between the theoretical model and the experimental data.