[Objective] To address the issue of component vibration and abnormal noise in transformers caused by harmonic intrusion during metallurgical production, this study investigates the evolution of metallurgical harmonic disturbances in multi-physical fields using a multi-physics coupling approach, combining simulation and experimental methods. [Methods] First, a coupling electromagnetic-mechanical-acoustic model of the transformer was proposed, taking harmonic disturbances into account. Electromagnetic force and vibration acceleration were selected as the characteristic parameters linking electromagnetic-mechanical and mechanical-acoustic fields, respectively. Based on electromagnetic coupling, the winding current, magnetic flux density, and electromagnetic force of the transformer were solved. The electromagnetic force was then used as the excitation for the mechanical model to calculate the vibration acceleration of the transformer core and windings. Subsequently, the vibration acceleration was used as excitation for the acoustic model to calculate the sound pressure and the variations in sound pressure level, thereby realizing the multi-field coupling process across electromagnetic, mechanical, and acoustic domains. The spatiotemporal distributions and variations of each field under various disturbance modes were simulated. The evolution of disturbances in the multi-physical fields was analyzed using the characteristic parameters. The effects of harmonic and interharmonic components' disturbances on the transformer's multi-field parameters were studied through simulation. Additionally, a test platform for dynamic simulation was built to collect vibration and noise signals from the transformer under different disturbance modes. [Results] The results showed that when metallurgical harmonics intruded into the transformer, the multi-field information of the components increased with higher load rate and harmonic frequency. Interharmonic components caused more significant disturbances to the transformer than harmonic components in adjacent frequency domain. The accuracy of the proposed model was verified through simulation-experiment comparisons. [Conclusion] Based on simulation and experimental results, the most significant interharmonic component 97 Hz in metallurgical harmonics is selected as a typical characterization parameter. A mapping relationship between different levels of the 97 Hz interharmonic and the vibration of transformer components is established, and an instability criterion is developed. When the 97 Hz interharmonic content reaches 15%, it causes severe instability in the internal electromagnetic and mechanical environments within the transformer. The identification method provides support for situational awareness and equipment protection for transformers under metallurgical harmonic intrusion.