Chiral sum-frequency generation (C-SFG) is an electric-dipole allowed non-degenerate second order nonlinear process which could be used to probe the chiral component x(2) in chiral interface and chiral bulk media.Being chemical and chiral selective, C-SFG imaging and spectroscopy technique are capable for label-free, achiral background free, in situ and realtime characterization of biomolecule and bioengineering sample.