The closed and the opened carbon nanotubes were prepared and examined separately as anodes of lithium batteries. Their first charge curves were almost the same, but their discharge curves were obviously different. For the closed carbon nanotubes: with the presence of pentagons and heptagons, the tube end was capped and Li cannot be inserted into the inner con of the tube. For the opened carbon nanotubes, with the absence of pentagons and heptagons, the tube end was opened and Li can be inserted into the inner core of the tube. The opened carbon nanotubes showed poorer cycling performance than the closed carbon nanotubes, the main reason is that the closed carbon nanotubes have smaller Warburg prefactor value than the opened carbon nanotubes.