As an industrial byproduct of oil refining, furfural extract oil from reduced-pressure route with high aromatic content was used to prepare heat-resistant condensed polynuclear aromatic (COPNA) resin for the first time. The basic properties of furfural extract oil and the resultant COPNA resin were characterized by infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H-NMR), thermogravimetric analysis (TGA) and elemental analysis (EA). The result showed that heat treated furfural extract oil was successfully used for the synthesis of heat-resistant COPNA resin. The average structural parameters of raw materials and prepared resin were calculated by the improved Brown-Ladner method, and the averaged molecular structure of the resin was obtained. The reaction mechanism for the synthesis of COPNA resin was suggested as an acid-catalyzed positive ion type polymerization.