The luminescence spectroscopy of the Al2O3 is widely used for sensing the stress in Al2O3-based materials. One promising approach that improves the spatial resolution of the luminescence spectroscopy is use of near-field optical system, which is effective to assess the localized stress in nano/micro-size structural components. Here, we perform the spectral analysis of near-field excited luminescence for stressed Al2O3, which shows abnormal asymmetry in the line shape that is not observed in conventional far-field measurement. For analysis, we employ the two models including different effects. The model of stress-gradient-based spectrum broadening fails to account for the asymmetry of the luminescence spectrum. In contrast, the model including vibronic states transition yields good matching of the measured spectrum line shape, indicating that the electron-phonon coupling in Al2O3 affects the appearance of the asymmetric line shape. The magnitude of electron-phonon interaction as well as the effect of the excitation method on the line shape are discussed.