C2H2 zinc-finger motif presents in 3% of proteins that are encoded in the human genome, and has the abilities to recognize DNA, RNA and protein.  With nearly 3 decades of efforts, the mechanisms of zinc-finger mediated biomolecule recognitions have been studied to various extents.  Zinc-finger binds into the major groove of DNA double helix, establishes an one-to-one recognition format between DNA bases and certain amino acids in a zinc-finger, and achieves specificity based on DNA sequences.  While RNA molecules show a large variety in their structures, zinc-finger recognizes RNA through the collected information of specially displayed bases and special backbone folding.  Initial studies have been performed on zinc-finger mediated protein-protein interactions.  Existing data indicate multiple recognition modes.  The studies on molecular mechanism have supported the development of engineered zinc-fingers, which have been introduced into applications.  For its wide existence, large functional diversity and potential in translational applications, zinc-finger deserves a systematic study in every aspect.