Polyimide foam (PIF) is a high-performance porous polymer material that has been utilized in environments requiring high heat resistance and structural stability, including advanced technologies such as aerospace and naval ships. In this study, polyester ammonium salt (PEAS) was used as a powder precursor and a rapid microwave-assisted foaming process was introduced to produce PIF with a uniform pore structure and excellent physical properties. The produced PIF demonstrated stable shape recovery behavior subsequent to mechanical deformation and exhibited excellent thermal stability. This study demonstrates the effectiveness of microwave foaming for the fabrication of high-performance PIF. In addition, PIFs fabricated by this method offer potential applications as lightweight structural materials suitable for extreme environments.