The olfactory perception is the process that the olfactory receptor is activated by odorous molecules, which induce the transduction of signal in the cell and the chemical information is transduced into electrical impulses. After the changed signal is transmitted to the brain, the whole perception process completes. OR gene belongs to the multigene family. The coded olfactory receptor proteins belong to the G-protein-coupled receptor (GPCR) superfamily and therefore are invariably seven-transmembrane domain(7TM) protein. Olfactory receptor protein plays an important role in olfactory perception and signal transduction process.