The Tropical Cyclone(TC) boundary layer contains many fine-scale coherent structures, which are closely associated with TC-related disasters. Increasing attention has been paid in studying the fine-scale structures in the TC boundary layer over the past 20 years to improve the forecast of TC intensity and structure. A significant progress has been achieved due to the improvements in observation, computation capacity, and the understanding of the associated mechanisms. This review focuses on the fine-scale coherent structures of the TC boundary layer in both the observational and numerical studies, especially on the horizontal rolls and tornado-scale vortices. Some suggestions and recommendations are provided for further understanding of the fine-scale structures in the TC boundary layer.