Abstract: The accuracy of flash parameters is critical to visual electrophysiological examination. An equivalent circuit model of the flash measurement system was established according to the characteristics of visual electrophysiological flashes. The influence of parameters of the flash measurement system on measurement error of flash waveform, intensity and duration was analyzed theoretically and experimentally. Xeon lamp and LED flash sources were tested. Experiments were carried out to investigate how measurement errors varied with parameters of the measurement system. The method for reducing the measurement errors respect to different application requirements was proposed, as well as the method to eliminate the theoretical errors when measuring the flash duration of LED and the flash intensity, which were demonstrated by experiments. The intensity and duration of LED flash were measured at different system parameters by using the proposed methods. Results demonstrated that the standard deviation of the flash intensity is 0.17% and that of the duration is 0.07%, which can be regarded as constants, showing good consistence with theoretical analysis.