Abstract: A new method based on the molecular self-assembly was proposed for the carbon fiber surface modification. The carbon fiber surface was first metallized by electroless Ag plating and then covered by organic compound self-assembly films. The surface-enhanced Raman scattering spectroscopy (SERS) analysis verifies that two nitrogen-containing or sulphur-containing aromatic heterocyclic compounds were chemisorbed onto the Ag-plated carbon fibers and formed a lie-down phase. XPS further proves the chemisorption of self-assembly films on the carbon fiber surface via the formation of S—Ag or N—Ag bonds. The interfacial bonding strengths of modified carbon fiber/epoxy composites are improved. The relationship between the structures of interfacial regions and properties of the micro-composites is revealed.