Abstract: The cutting of single-walled carbon nanotubes (SWNTs) with γ radiation in the presence of sulfuric acid was researched systemically. The photoacoustic effect of SWNTs caused by laser and γ radiation in aqueous solution was initially investigated. Moreover, the proposed mechanism for the cutting process of SWNTs was also analyzed. The short SWNTs were characterized and analyzed with transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis) and Raman spectroscopy. Results indicate a synergetic effect between the γ radiation and sulfuric acid oxidation on the cutting of SWNTs. The resulted short nanotubes have a length distribution of 200-400 nm. Moreover, it can be uniformly dispersed in water for one week. The cutting approach induces the production of a certain number of —OH, —COOH functional groups on the short SWNTs. In addition, SWNTs irradiated by Q switch pulsed laser will occur a large photoacoustic effect in the solution, while SWNTs irradiated by γ exist a much weaker photoacoustic effect.