Proposals for studying topological superconductivity and Majorana bound states in a nanowire proximity coupled to superconductors require that transport in the nanowire is ballistic. Previous works on hybrid nanowire-superconductor systems have shown evidence for Majorana bound states, but these experiments were also marked by disorder, which disrupts ballistic transport. In this paper, we demonstrate ballistic transport in the InSb nanowires interfaced directly with superconducting Al by observing quantized conductance at zero-magnetic field. Additionally, we demonstrate that the nanowire is proximity coupled to the superconducting contacts by observing Andreev reflection. These results are important steps for robustly establishing topological superconductivity in the InSb nanowires.