Considering the geometrical figure of tube and tip, we calculated the surface charge density relative distribution curve of metallic carbon nanotube. Compared with the previous theoretic result, our curve rose apparently without fluctuation, and the ratio of tip charge quantity decreased. Furthermore, we studied the influence of length, radius and aspect ratio on the charge density relative distribution curve, showing that length and radius play an important role in relative charge distribution of tube and in tip respectively. Without considering other aspects, carbon nanotubes with the same a...