It is important in fast ignition (FI) to drill a channel in the coronal plasma by a long intense pulse firstly, since we expect the following ultra-intense pulse will reach more easily the dense core to obtain the fuel burning. An experimental design to study the plasma channeling was presented at two beams laser sub-picosecond (SPS) Facility of National Laboratory of High Power Laser and Physics. One beam with 1.053 μm and 350 ps full width at half maximum (FWHM) was used to form the pre-plasma. And then, a most part of another one with the same wavelength and 1 ps FWHM was focused on the plasma for channeling. The rest part of the 1 ps laser beam, frequency quadrupled to λ=0.263 μm, was as a probe used in Normaski polarization interferometry to diagnosis the electron density distribution of the channel.