Abstract: Polyimide resins and their composites have a lot of excellent properties such as heat resistance, dielectric properties, insulation performance, friction resistance, etc. They play an irreplaceable and important role in the fields of aerospace, rail transit, weaponry, and microelectronics. Polyimide resins and their composites have a wide range of applications and show outstanding performance in every application area. Researchers at home and abroad have been enthusiastic about the research of high-performance polyimide resin and their composites. We mainly review the melt processability, solubility, and dielectric properties modification of thermoplastic polyimide resins in recent years, as well as the functional research of their composites in terms of friction resistance, electrical conductivity, heat conduction, etc. Moreover, We review the research progress on temperature resistance grade, toughening modification of thermosetting polyimide resins, and the functional research of their composites in terms of friction resistance, electromagnetic shielding, high thermal conductivity, etc. Finally, we look forward to the future of thermoplastic and thermosetting polyimide resins and their composites.