A novel epoxy resin modifier, phosphorus-containing epoxide siloxane (OPS), was prepared from the sol-get reaction of GPTMS-DOPO, which was synthesized by the reaction of 3-glycidoxypropyltrimethoxysilane (GPTMS) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). OPS with superfluous epoxide groups were confirmed by Si-29 NMR, gel permeation chromatography (GPC), elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Compared with those with no epoxide group and unmodified resins, the hybrid epoxy resins exhibited high glass-transition temperature (71,), good limited oxygen index (LOI) and tensile strength.