Abstract: A mechanothermal method is one of the methods used for the large scale production of carbon nanotubes (CNTs). The flake graphite was milled under argon atmosphere to nanometer sized carbon in amorphous state, and was then annealed at high temperature(1 350-1 380℃) to yield CNTs. The milled graphites and CNTs were characterized by XRD, SEM, FE-TEM, HRTEM, and Raman spectroscopy. It is found that the CNTs have a length of several millimeters and a diameter of 30-70 nm with different morphologies. The spring-like MWCNTs have a high aspect ratio (~1000) and a high crystallinity (I_D/I_G~0.03).