Carbon nanotubes posses distingishing physical and chemical properties, including high mechanical strength, peculiar metallic properties, semi-conductivity, and hydrogen storage ability etc. They are believed to be excellent functional and structural materials. The recent discovery and research in carbon nanotube materials has provided the basis for groundbreaking advances in materials science, chemistry and electrical engineering. This article describes the properties of carbon nanotubes and their applications on scanning probe microscope, electronic components, active materials, structural materials, and hydrogen storage.