Abstract: The lightning continuing current is an important form of transferring charge from the cloud sources to the earth. The thermal effect generated during this process may cause serious damage to natural environment as well as to the human habitats. This thermal effect is associated with the current wave shape and the transferred charge. Here, in the simulated high voltage laboratory, the simulated lightning continuing current with a peak range from 233.8 to 633.3 A was generated in the arc discharge channel gap. The channel luminosity was synchronously measured by two photodetectors which are sensitive to red light (a detection wavelength ranging from 200 nm to 1000 nm with the peak response of 600 nm) and near-infrared light (a detection wavelength ranging from 400 nm to 1000 nm with the peak response of 800 nm), respectively. The results show that the luminosity waveform measured under the normal channel can follow the current waveform faithfully while the tortuosity of arc channel will lead to the waveform distortion of channel luminosity. This distortion is specifically manifested as a significant 'sag' in the continuing stage of luminosity waveform, and the probability of distortion in all luminosity waveforms is 19.8%. The relationship between the simulated continuing current and channel luminosity was further investigated. A strong linear correlation was found between the luminosity peak and the current peak, as well as between the luminosity-time integration and the current charge transfer under different spectral responses. The obtained results provide a new approach to accurately estimate the continuing current waveshape and the transferred charge by using the correlation between current and luminosity.