Abstract: Capacitor is one of the essential components in modern electronic devices, with the performance of the dielectric layer being critical to overall functionality. Increasing the doping of filler usually enhances the dielectric constant of polymer-based composite dielectrics; however, excessive doping can lead to interfacial polarization and agglomeration, resulting in increased dielectric losses and rapid reduction of capacitance under high-frequency electric fields. In this study, AlOC-58NC containing highly polar amino isonicotinate was used as a polymer dopant, and its effect on the dielectric performance of film capacitors was investigated. The results show that as the doping amount of AlOC-58NC increases, the capacitance of the film gradually rises, with a magnitude of increase of up to 2.7 times (25 Hz). The large molecular size of AlOC-58NC (approximately 2.5 nm) contributes to stronger polarization and dielectric response, resulting in a minimal decrease of the capacitance at high frequency of only 23.6% as compared with that at low frequency and maintaining dielectric losses at a low level (D < 0.1). This study successfully breaks the inherent balance between dielectric constant and loss, providing a novel approach for the design of polymer composite dielectric materials.