The third harmonic generation of the opened-end semiconductor single-wall carbon nanotube is studied by using the density matrix theory with effective-mass approximation. It is found that the third harmonic generation increases with an increase in the tube radius. There are not only one- and three-photon resonant peaks, but also the two-photon resonant peak, which is consistent with the experimental results. (c) 2006 Elsevier B.V. All rights reserved.