  The shear-flow-driven instability can play an important role in energy
transfer processes in coronal plasma. We present for the first time the
observation of a kink-like oscillation of a streamer probably caused by the
streaming kinkmode Kelvin-Helmholtz instability. The wave-like behavior of the
streamer was observed by Large Angle and Spectrometric Coronagraph Experiment
(LASCO) C2 and C3 aboard SOlar and Heliospheric Observatory (SOHO). The
observed wave had a period of about 70 to 80 minutes, and its wavelength
increased from 2 Rsun to 3 Rsun in about 1.5 hours. The phase speeds of its
crests and troughs decreased from 406 \pm 20 to 356 \pm 31kms^{-1} during the
event. Within the same heliocentric range, the wave amplitude also appeared to
increase with time. We attribute the phenomena to the MHD Kelvin-Helmholtz
instability which occur at a neutral sheet in a fluid wake. The free energy
driving the instability is supplied by the sheared flow and sheared magnetic
field across the streamer plane. The plasma properties of the local environment
of the streamer were estimated from the phase speed and instability threshold
criteria.
