The effect of the initial velocity of boundary atom on the motion of an atomic chain is studied by the one-dimensional Frenkel-Kontorova model. The obatined results show that the three phases could be observed in our simulation, these being harmonic phase when vv1, choatic phase when v1vv2 and uniformity phase when vv2. It is aslo shown that the two critical velocites(v1,v2) are strongly influenced by the number of atoms and the depth of the substrate potential.