The paper presents constitutive model of the aluminium metal matrix composite reinforced by a silicon carbide. Developed equation includes an empirically estimated term which takes into account softening effects of the composite due to reinforcement damages at a large strain. Experimental investigation of the aluminium based MMCs reinforced by silicon carbide of volume fraction equal to 0%, 10%, 20% and 30% were carried out. Tests were conducted at wide range of strain rates and large magnitudes of strains. Comparison between experimental and predicted data shows that the elaborated model may be applied for composite materials in computer simulations of large deformations.