Heterointerface engineering has been attracting extensive scientific attention for novel interfacial properties and functionalities. In this study, artificial oxide superlattices are fabricated by inserting 5d transition-metal oxides SrIrO3 to ferromagnetic La2/3Sr1/3MnO3 with the expectance of pronounced spin–orbit coupling. The interface structure and elemental distribution of the La2/3Sr1/3MnO3/SrIrO3 superlattices have been investigated at an atomic scale using aberration-corrected transmission electron microscopy and electron energy loss spectroscopy. The results show that the epitaxial strain plays a dominant role in determining the thickness gradient growth of the superlattices film. Besides, the intermixing at the interface was observed, which has an important effect on the electronic structure thus the further charge redistribution of the heterointerface. The asymmetrical oxygen octahedral rotation with weak oxygen octahedral coupling at the interface was quantitatively measured by directly imaging the oxygen octahedron at the atomic scale.