The oil leakage fault detection of traction transformers isa crucial component of Electrical Multiple Unit (EMU) operation fault detection. In the near-infrared image of the bottom plate collected by the trouble of moving the EMU detection system, the characteristics of leakage transformer oil traces are similar to those of water traces, which cannot be distinguished by the trouble inspectors and image recognition algorithms, resulting in a high false alarm rate of the oil leakage fault and affecting the operation and maintenance efficiency of the train.Water lacks fluorescence properties, whereas mineral transformer oil exhibits ultraviolet fluorescence, so fluorescence imaging can differentiate the two traces. Moreover, varying operating seasons, regions, and periodsof EMU expose the leaked transformer oil to diverse environmental conditions, affecting its fluorescence properties. The fluorescence properties of the leaked oil decide the choice of excitation light source wavelength and imaging band for the fluorescence imaging system.Hence, samples under different temperatures and light conditions are first prepared to explore the fluorescence properties of mineral transformer oil used by EMU and the impact of two major environmental factors, temperature, and light, on its fluorescence properties. Then, the three-dimensional fluorescence spectra of the samples were collected by the fluorescence spectrometer and subsequently analyzed, the fluorescence characteristics of the samples and the effect of temperature and illumination on the location and intensity of fluorescence characteristic peaks. The results show that the mineral transformer oil for EMU has two strong fluorescence excitation/emission peaks located at 350/382 and 350/402 nm, respectively. The increase in temperature causes a decrease in fluorescence intensity but does not change the position of the fluorescence peaks. The increase of light intensity and the extension of light duration cause a decrease in fluorescence intensity but do not significantly change the position of fluorescence peaks. The experimental results provide experimental evidence and data support for fluorescence imaging to detect the leakage fault of mineral transformer oil for EMU.