Abstract: A novel phosphorus-containing epoxy resin with good solubility and high thermal stability was obtained via the reaction of diglycidyl ether of bisphenol A with 2-(5,5-dimethyl-4-phenyl-2-oxy- 1,3,2-dioxa- phosphorin-6-yl)1,4-benzenediol, and its structure and relative molecular weight distrubutuin were characterized with elemental analysis, FTIR and gel permeation chromatography (GPC). A phenol formaldehyde novolac resin (PN) was used as curing agent to prepare a thermoset resin with the phosphorus-containing epoxy resin. The thermal properties and thermal degradation behavior of the thermoset resin was investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Phosphorus-containing cured resin exhibited higher glass transition temperature (165℃) than the ordinary disphenol-A epoxy resins (129℃) due to the high rigidity of its molecular chain. TGA studies showed high residue (700℃ 31%) of the PN-cured epoxy resin due to the presence of phosphorous in the main chain. A sample containing 2.25% (mass ratio) phosphorus had limiting oxygen index values of 29.5. The developed resin may be used potentially in electronic industries.