Abstract: Polymethacrylate imide (PMI) foam is widely used in aerospace field because of its superior performance. This paper mainly studies the functional characteristics of PMI foam in the field of cartridge adapter, and mainly studies its compression creep characteristics at room temperature. According to the working conditions and creep characteristics of polymer materials, the "time strengthening" model was adopted to design experiments, and the PMI foam with densities of 0.075 g/cm³ and 0.110 g/cm³ were respectively tested for 180 days under normal temperature compression creep. By analyzing and fitting the experimental data, the compression creep life of two PMI foam with different densities at room temperature and 1250 N was predicted. The compression creep failure life of PMI foam with density of 0.075 g/cm³ is about 11 years. The density of 0.110 g/cm³ PMI foam is about 53 years, and the reliability of the model is verified and analyzed.