2519A aluminum plate was shot obliquely by an incendiary projectile with the diameter of 7.62mm at impact velocity of 818m/s. The penetration inhomogeneities of the crater of 2519A aluminum target plate were investigated with optical microscopy (OM), scanning electron microscopy (SEM). Melted substance, a mixture of the target material and the projectile was found at the interface of target and projectile. Different microstructural characteristics were observed along the crater depth. Grains were elongated near the entrance area, while severely kinked grains and adiabatic shear bands were present in the middle region, and microbands, as well as abnormal grown grains, appeared at the crater bottom. The failure form of target is mainly ductile expanding.