A novel naphthyl-based self-catalyzed phthalonitrile monomer was prepared via nucleophilic displacement reaction. The structure was characterized by Fourier infrared spectrum(FT-IR) and nuclear magnetic resonance(1H NMR). The polymerization mechanism was explored. Thermal properties were characterized by differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA), which demonstrated self-promoted behavior and excellent heat resistance. A novel naphthyl-based self-catalyzed phthalonitrile monomer was prepared via nucleophilic displacement reaction. The structure was characterized by Fourier infrared spectrum (FT-IR) and nuclear magnetic resonance (1H NMR). The polymerization mechanism was explored. differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), which demonstrated self-promoted behavior and excellent heat resistance.