In this paper, we have investigated both the process of rare-gas atoms ( He, Ne, Ar, Kr, Xe) injected into single-wall carbon nanotube (SWNT) and the mechanical oscillatory behavior of rare-gas atoms sliding in a SWCNT by using molecular dynamics simulations. The minimal diameters of SWCNT to encapsulate rare-gas atoms are obtained, which are from 6.246 to 7.828 angstrom. The threshold energies to encapsulate rare-gas atoms in SWCNT are also presented, which are less than 0.15 eV/atom. The oscillatory frequencies of the encapsulated atoms in zigzag SWCNT have been studied. The oscillatory frequencies are insensitive to the initial kinetic energy, but they are sensitive to the lengths and the radius of the tube, and they decrease as the length and the radius of the tube increases.