Abstract: To investigate the impact resistance and damage failure mechanisms of a composite aeroengine case, the subscale containment test was conducted on a high speed spin tester and numerical simulations were carried out using an explicit transient dynamic code. The impact process between the released blade and the composite case was investigated to obtain the containment mechanism of the composite case. The influences of the thickness on the failure mode and containment capacity were analyzed to study the correlation of the case thickness and the energy absorption. Containment process usually involves 3 continuous impacts. The failure modes are significantly different in the inner wall and the outer wall of the composite case. The released blade bends more severe and the energy absorption by the composite case increases exponentially with the increase of case thickness.