A series of trifunctional epoxy resins were successfully synthesized by the condensation of 2,6-dimethylol-4-methylphenol with phenol, cresol, 2,6-dimethylphenol or 2-naphthol, respectively, followed by epoxidation with a halohydrin. The structures of the synthesized triphenols were characterized by elemental analysis (EA), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectrometry, including H-1-NMR and C-13-NMR. The resulted epoxy resins were cured with 4-4＇-diaminodiphenyl sulfone (DDS), and the cured products were investigated. The cured trifunctional 2,6-bis-(2-glycidyloxy-1-naphthyl-methyl)-4-methyl phenyl glycidyl ether had the highest glass transition temperature, highest thermal stability, the lowest coefficient of thermal expansion, and lowest moisture absorption of the epoxy resins studied. The internal stress of cured naphthalene-containing epoxy resin was reduced by modification with 12 wt % amino-terminated polydimethyl siloxane (ATPDMS), while the glass transition temperature was only slightly depressed. Phase separation of the silicone rubber-modified epoxy matrix was characterized by SEM.