Abstract: 2-Hydroxyethyl-pyridyl disulfide (PⅠ) was synthesized from the 2,2-dithiodipyridine, 2-mercaptoethanol using the acetic acid as the catalyst. 4-Cyano-4-((thiobenzoyl)sulfanyl) pentanoic acid-2-pyridyl disulfide ester(PⅢ)，a novel RAFT chain transfer agent, was synthesized from the PⅠand 4-cyano-4-((thiobenzoyl)sulfanyl) pentanoic acid (PⅡ) using 1-(3- dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine as the catalyst.PMMA was prepared from the RAFT chain transfer agent PⅢ,initiator AIBN and Methyl Methacrylate(MMA) through RAFT polymerization. 1H-NMR was used to analyze the molecular structure of the chain transfer agent and GPC was used to analyze the molecular weigh and molecular weight distribution of PMMA. Results showed that the group of pyridyl disulfide with the function of thiol based click chemistry was converted to the end of PⅡ. The dithioester RAFT chain transfer agent(PⅢ) with the function of thiol based click chemistry was synthesized successfully. PMMA with narrow molecular weight distribution was prepared by using the chain transfer agent PⅢ.