||The 0.42 nm-sized single-walled carbon nanotubes (SWNTs) are synthesized by pyrolysis of large quantities of tripropylamine (TPA) in the one-dimensional channels of zeolite single crystal (AlPO4-5). These singular diameter SWNTs are mono-dispersed inside the channels of AFI. First of all, the effects of fabrication conditions on the formation of the SWNTs are studied by the Degree of Polarization of samples, so that an effective growth temperature of tubes is determined at 530-580°C. Besides, a fingerprint of SWNTs Raman peak is observed in the high frequency region at about 1600 cm-1. In low frequency region, a diameter dependent of SWNT Raman peak, radial breathing mode, is also found at about 530 cm-1, which indicates the diameter of these SWNTs is 0.42 nm. Furthermore, a direct evidence of existence of SWNTs is confirmed by High resolution Transmission Electron Microcopy (HRTEM) image. This HRTEM image shows that there are many SWNTs with 0.42 nm diameter inside the AFI channels after chemical etching. This HRTEM image result is consistent with the Raman scattering result. Finally, possible structure of these 0.42 nm-sized SWNTs is suggested to be a (5,0) zig-zag tube after considering three approaches: tubule energetic stability, capping properties of the tube and the period matching between AFI crystal and this tube. The production of mono-dispersed and single diameter-sized SWNTs in 3D array represents an essential role in the development and application of carbon nanotubes.