Channeling phenomena of He, Ne, Ar and Kr ions at energy (200-5000eV) in single-wall carbon nanotubes (SWCNTs) are investigated by molecular dynamics simulation with analytical potentials.The critical angles for the particles to be channeled in an SWCNT are analyzed.In the incident energy range of 200-5000 eV, it is found that the ion energy dependence of the critical angle obeys an improved Lindhard equation which is closely related to the ratio of nuclear charge number to atomic mass Z/M.The critical angle for different types of ions channeling in SWCNTs is determined by both the atomic nuclear charge and mass.