Abstract: Taking domestic and imported centrifugal casting austenitic stainless steel as the research object, six batches of samples with different thermal aging time were prepared by accelerated thermal aging method. The mechanical properties of the two materials after thermal aging were compared and analyzed. The microstructure of the samples was systematically characterized by optical microscope, scanning electron microscope and transmission electron microscope. The results show that the performance indexes of the two materials met the requirements of RCCM-M3406 standard. The chemical composition control and microstructure optimization of the main pipeline material would have a significant impact on its thermal aging performance. The formation and development rate of precipitates was not consistent with the decrease rate of mechanical properties of materials.