Kinematic Evolution of a Slow CME in Corona Viewed by STEREO-B on 8 October 2007

We studied the kinematic evolution of the 8 October 2007 CME in the corona based on Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) onboard satellite B of Solar TErrestrial RElations Observatory (STEREO). The observational results show that this CME obviously deflected to a lower latitude region for about 30$^\circ$ at the beginning. After this, the CME propagated radially. We also analyze the influence of the background magnetic field on the deflection of this CME. We find that the deflection of this CME at an early stage may be caused by the nonuniform distribution of the background magnetic field energy density and that the CME tended to propagate to the region with lower magnetic energy density. In addition, we found that the velocity profile of this gradual CME shows multiphased evolution during its propagation in COR1-B FOV. The CME velocity first kept at a constant of 23.1km.s-1. Then, it accelerated continuously with a positive acceleration of 7.6m.s-2.