In order to study the influence of the stray current of urban rail transit on the dc magnetic bias characteristics of a 500kV transformer in Shanghai along the line, the dc, vibration and noise characteristics of the transformer neutral point after the normal operation, peak operation and shutdown of rail transit were tested by means of synchronous measurement of multiple physical quantities. Transformer neutral DC, vibration, noise and rail transit load change show consistent change law, rail transit peak operation, transformer neutral DC maximum 30.2A, transformer will appear different degrees of

polarization phenomenon, noise is 10dB higher than normal operation. It is proved that the stray current caused by rail transit operation will affect the dc, vibration and noise of the neutral point of the transformer along the line. The research results can provide reference for metro line planning and power grid development planning.