  The detection of primordial B-mode polarization is still challenging due to
the relatively low amplitude compared to the galactic foregrounds. To remove
the contribution from the foreground, a comprehensive picture of the galactic
magnetic field is indispensable. The Velocity Gradient Technique (VGT) is
promising in tracing magnetic fields based on the modern understanding of the
magneto-hydrodynamic turbulence. In this work, we apply VGT to a HI region
containing an intermediate velocity cloud and a local velocity cloud, which are
distinguishable in position-position-velocity space. We show that VGT gives an
excellent agreement with the Planck polarization and stellar polarization. We
confirm the advantages of VGT in constructing the 3D galactic magnetic field.
