Phenyl cycloaliphatic epoxy-silicone oligomers (Ep-Ph-SiO) with different contents of benzene rings and epoxy groups were synthesized via sequential hydrosilylation reactions of methylhydrogen silicone oil by attaching styrene first, which was followed by reacting with 4-vinyl-1-cyclohexene-1,2-epoxide in the presence of Lamoreaux catalyst. The contents of benzene rings and epoxy groups in the monomers were determined by 1H-NMR. The refractive indices (RIs) of the obtained oligomers were measured and the cationic photo-polymerization of these oligomers was studied by using triarylsulfonium hexafluorophosphate (P-S) as photo-initiators exposed to a high-pressure mercury lamp. The results showed that the phenyl cycloaliphatic epoxy-silicone oligomers exhibited higher photo-polymerization activity than diglycidyl ether of bisphenol-A epoxy resins and the benzene rings could improve the RIs of cycloaliphatic epoxy-silicones.Cited