Abstract: The influences of curing reaction temperature and time, toughening agent and thickening agent addition amounts on rheological properties of phenolic resin were investigated using rheometer. The glass fiber reinforced phenolic prepregs were also prepared to fabricate glass fiber/phenolic-Nomex honeycomb cored sandwich composites by co-curing technology with Nomex honeycomb core, and the adhesion properties of skin-core were measured. The results show that the viscosity of the modified phenolic resin at elevated temperature increases a lot and flow behavior is also well improved, the interfacial adhesion between the as-prepared prepreg and Nomex honeycomb core enhances obviously and the climb drum peel strength of the as-prepared sandwich panel can achieve to above 15 N·mm/mm when the mass ratios of toughening agent and thickening agent addition amounts are 5% and 3% to the pure phenolic resin, indicating the self-adhesive characteristics of the modified phenolic resin and its prepreg. Additionally, it can further increase the adhesion strength of skin-core for glass fiber/phenolic-Nomex honeycomb cored sandwich composite by applying a moderate heating profile in co-curing process.