We propose a novel and compact all-optical tunable filter with embedded preamplifier and channel selector. This filter is based on cross-Raman scattering (XRS) in a silicon nanowire waveguide, suitable for multichannel optical communications. Tuning is performed by means of tuning the pump center wavelength. With this tuning approach the separation between the pump wavelength and that of the desired channel should equal the Raman shift in Si. Spanning over 40 optical communication channels following the ITU-T G.694.1 standard ( $100\mathrm{GHz}$ grid), our simulation results have demonstrated an excellent channel selectivity and tunabilty for the proposed all-optical filter. The XRS process in Si nanowire has amplified the desired channel by about $11.5\pm 0.38\mathrm{dB}$ , while the suppression ratios for the first and the second neighboring channels are about $28\pm 0.25$ and $33.6\pm 0.31\mathrm{dB}$ , respectively.