Abstract: The mechanical experiment, hysteresis loop test and multi-magnetic parameters test were carried out after accelerated thermal aging of 17-4PH under 350℃. Results show that the impact energy of 17-4PH decrease while the hardness increase after thermal aging. The hysteresis loop shows that thermal aging has no impact on macroscopic magnetism of 17-4PH and the magnetic parameters show no regular change. Through the application of artificial neural network, the proper node and algorithmic was chosen to build the precise module to evaluate the thermal aging of 17-4PH, which provide a new way to evaluate the thermal aging of 17-4PH.