The single-wall carbon nanotubes functional modified with tetrazoly groups(SWCNTs-CN₄) was firstly prepared by diazo-reaction on the wall of SWCNTs, and was characterized. Attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy show that the tetrazolyl groups are introduced to the surface of SWCNTs by covalent bond and hold the structure of five-ring. X-ray photoelectron spectroscopy (XPS) indicates that the N on the SWCNTs-CN₄ is about 14.8%. The ratio of tetrazolyl groups to carbon atoms of SWCNTs-CN₄ is about 4.9/100 by XPS calculation.