  We investigate the interaction of a periodic solution and one-soliton
solution for the spin-polarized current in a uniaxial ferromagnetic nanowire.
The amplitude and wave number of the periodic solution for the spin current
have the different contribution to the width, velocity, and the amplitude of
soliton solution, respectively. Moreover, we found that the soliton can be
trapped only in space with a proper condition. At last we analyze the
modulation instability and discuss dark solitary wave propagation for the spin
current on the background of a periodic solution. In some special cases the
solution can be expressed by the linear combination of periodic solution and
soliton solution.
