Abstract: Polyamide acid （PAA） solutions were synthesized using pyromellitic dianhydride （PMDA） and 4,4'-oxydianiline （ODA） as monomers within the PMDA-ODA system, employing N,N-dimethylacetamide （DMAC）, dimethyl sulfoxide （DMSO）, N,N-dimethylformamide （DMF）, and N-methyl-2-pyrrolidone （NMP） as solvents. The rheological properties of these PAA solutions were characterized via rotational rheometry, encompassing flow ramp tests, small-amplitude oscillatory frequency sweeps, and small-amplitude oscillatory temperature sweeps. The flow behavior of the system was described using the power-law model. Results demonstrate that the system exhibits pseudoplastic （shear-thinning） non-Newtonian behavior, albeit exhibiting only mild non-Newtonian characteristics. Both the storage modulus （G'） and loss modulus （G''） were observed to increase with rising angular frequency. The evolution of the moduli during heating was analyzed by combining in situ Fourier transform infrared spectroscopy and thermogravimetric analysis （TG）. The findings reveal that during the initial heating stage, the moduli are significantly influenced by solvent volatility; the concurrent increase in solution concentration due to solvent evaporation constitutes the primary factor driving modulus enhancement. For solvents exhibiting lower volatility, the PAA solution modulus initially decreases with increasing temperature due to intensified molecular thermal motion, followed by an increase. A distinct modulus plateau region emerges during the intermediate heating stage, where modulus variations remain relatively minor. Beyond 130 °C, a pronounced imidization reaction occurs within the system, triggering a sharp increase in modulus and a transition from viscous-dominant to elastic-dominant behavior. After reaching 180 ℃, the storage modulus exceeds 10⁶Pa.