Abstract: This paper reviews the progress on the mechanical behavior of carbon nanotubes and carbon-nanotube-basedcomposites. Firstly, the structure stability and mechanical properties of carbon nanotubes such as theoretical predictions and experimental results are introduced. Secondly, developments on carbon-nanotube-based composites are summarized, including carbon nanotube-polymer composites, carbon nanotube-metal composites and carbon nanotube-ceramics composites. These composites will benefit from the exceptional mechanical properties of carbon nanotubes, but one must pay attention to the problem of load transfer efficiency. Finally, some future development trends are also presented.