The ternary alloy InAsSb of the low Sb component as the buffer layer, which reduces the mismatch of the film, was grown on the GaSb (100) substrate by using the molecular beam epitaxy , and then regrown the InAs film. Real-time in situ monitoring by reflection high energy electron diffraction throughout the growth process. Following the growth of the InAs film, the electron diffraction pattern showed a clear reconstitution line, with the surface of the film having atomic flatness. Atomic Force Microscopy is used to characterize InAs films, and the results show that the roughness of epitaxial InAs film on the InAsSb buffer with lower Sb components is reduced by about 2.5 times than the roughness of epitaxial InAs film on the InAsSb buffer with higher Sb components. X-ray diffraction and simulation were performed for epitaxial InAs films on ternary alloy InAsSb buffer with different Sb composition. The results show that the full width half maximun of the diffraction peak of the epitaxial InAs film on the lower Sb composition of InAsSb buffer layer is smaller. It is indicated that the InAsSb with a low Sb component acting as a buffer layer can reduce the internal stress of the InAs film and can improve the crystal quality of the InAs film. The luminescence properties of InAs films with high crystal quality were studied by photoluminescence spectroscopy. The luminescence peak of InAs is about 0.418 eV at 10 K, which is free exciton luminescence.