摘要： Low-dimensional narrow band gap III?V compound semiconductors, such as InAs and InSb, have attracted much attention as one of promising platforms for studying Majorana zero modes and non-Abelian statistics relevant for topological quantum computation. So far, most of experimental studies were performed on hybrid devices based on one-dimensional semiconductor nanowires. In order to build complex topological circuits toward scalable quantum computing, exploring high-mobility two-dimensional (2D) III?V compound electron system with strong spin?orbit coupling is highly desirable. Here, we study quantum transport in high-mobility InSb nanosheet grown by molecular-beam epitaxy. The observations of Shubnikov-de Hass oscillations and quantum Hall states, together with the angular dependence of magnetotransport measurements, provide the evidence for the 2D nature of electronic states in InSb nanosheet. The presence of strong spin?orbit coupling in the InSb nanosheet is veri?ed by the low-?eld magnetotransport measurements, characterized by weak antilocalization e?ect. Finally, we demonstrate the realization of high-quality InSb nanosheet?superconductor junctions with transparent interface. Our results not only advance the study of 2D quantum transport but also open up opportunities for developing hybrid topological devices based on 2D semiconducting nanosheets with strong spin?orbit coupling.