Transformer vibration analysis yields critical information with practical implications. Examining vibration variations throughout the aging process of transformers contributes significantly to understanding the rules governing these changes and assessing internal structural aging. The interplay between mechanical vibration, thermal aging, and the resistance of transformer cores and windings fosters a progressive degradation of the internal structure. However, the relationship between this internal deterioration and changes in the external casing’s wall vibrations remains elucidated. In order to study the synergistic effect of mechanical-thermal aging on the deterioration of the internal structure performance of the transformer, this paper designed an experimental platform for the aging of the internal structure of the transformer and collected the full-cycle vibration data of the internal pressure data and the vibration of the outer case wall of the transformer through continuous overloading operation for 60 days, and carried out vibration entropy, specific gravity of the fundamental frequency, and comprehensive correlation analyses on the data. The study shows that the internal structure pressure fluctuates and decreases during thermal aging, and the two indicators, vibration entropy, and fundamental frequency specific gravity, have opposite trends. This study can provide a reference role for analyzing the deteriorated vibration characteristics under the combined effect of machine-heat aging and diagnosing the location of the deployment points.