This study elucidates the electron emission properties of GaAsN/GaAs quantum well containing N-related localized states under illumination. The N-related localized states in a GaAsN quantum well (QW) are identified as both optical and electrical electron trap states. The mechanisms for the responses of current-voltage (I-V) measurement under illumination and photocapacitance are investigated. N-related localized states in GaAsN QW can extend response range and response sensitivity on photocapacitance, and produce an additional current path for photo-generated electron-hole pairs. Furthermore, exactly how illumination influences the electron emission rate of GaAsN QW electron state is examined. The electron emission rate of GaAsN QW electron state can be modulated by different incident photon energy, which is due to the modulation of depletion width of the bottom GaAs.