Propylene Glycol, with molecular formula C3H8O2 and structural formula,is colorless transparent liquid. Its melting point is -59.5℃ and boiling point is 187.3℃,and can be mixed or solvent with water, alcohol and several organic agent. Propylene glycol is a raw material for producing unsaturated of plasticizer, dehydrant, surface active agent, firming agent and binder. Moreover, PG can be used as antiseptics, ice inhibitor and moisture preserver of tobacco