||Single wall carbon nanotubes were prepared by pyrolyzing hydrocarbon molecules of tripropylamine (TPA) in the 1-nm-sized channels of AIPO4-5 (AFI) zeolite crystals. Techniques such as differential scanning calorimetric, thermalgraviatry and mass spectrum were used to investigate the formation process of the 0.4nm SWNTs inside the AFI channel. Ethylene was used to improve the sample quality. Lithium was doped into 4 Å carbon nanotubes by using vapor doping method. The Raman spectra of the doped SWNTs were characterized by downward shifting of the tangential mode and upward shifting of the radio-breathing mode with respect to the spectra of pristine CNT. This phenomena was explained by doping induced charge transfer and change of resonant condition in ultra small SWNTs.