Carbon nanotubes have been grown by gas sourer molecular beam epitaxy with the presence of Ni catalyst. Some nanotubes show thinner bases compared with their heads. The influence of initial Ni layer thickness as well as growth temperature on the nanotubes formation is studied. The growth of carbon nanotubes heavily depends on the size of the metal droplets and growth temperature. Raman spectra show graphite and glassy carbon structure for too thick and too thin initial Ni layer films, respectively.