A diglycidyl ether type epoxy resin from bisphenol A, E-51, was cured by methylhexahydrophthalic anhydride (MeHHPA) and then decomposed in near-critical water without any additives. The effects of the experimental parameters such as the reaction temperature, reaction time, pressure, and feedstock ratio on the percentage of decomposition were investigated to obtain optimized reaction conditions. The results revealed that the percentage of decomposition can be enhanced by increasing either temperature or reaction time. At 260 degrees C, it initially increased with higher pressure and then decreased dramatically when the pressure further was reduced to the saturated water vapor pressure. The kinetics study of the epoxy decomposition was also carried out by monitoring the glass transition temperature of the solid product using differential scanning calorimetry. The decomposition equation was established and the activation energy was calculated to be 123.5?kJ?mol1.