Preparing biomass-based epoxy resin with high temperature resistance and flame retardancy is still an appealing yet challenging task. Now, a high-temperature resistant and flame-retardant resveratrol-based epoxy (RESEP) has been synthesized through a facile one-step method. The structure of RESEP was established using FTIR and NMR spectroscopy. RESEP and petroleum-based epoxy diglycidyl ether of bisphenol A (DGEBA) were each cured with 4,4-diaminodiphenyl methane (DDM) to prepare RESEP/DDM and DGEBA/DDM. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing, thermogravimetric analysis (TGA), thermogravimetric analysis-infrared spectroscopy (TG-IR), scanning electron microscopy (SEM), limiting oxygen index (LOI) and the UL-94 vertical burning test were used to systematically evaluate the properties of RESEP and RESEP/DDM. The glass transition temperature (T-g) of RESEP/DDM is 335 degrees C, which is significantly higher than that of DGEBA/DDM (168 degrees C). In addition, RESEP/DDM displays good thermogravimetric performance and flame retardancy. Typically, it displays a UL-94 V-0 rating, an LOI value was as high as 31.8%, and a char yield as high as 38.6% (800 degrees C). The results reported indicate the possibility of preparing biomass-based epoxy resin with high temperature resistance, flame retardancy and mechanical properties, which is potential to be utilized in the fields of electronics and aerospace.