The invention relates to a discharging current measurement device of a lightning arrester. The lightning arrester is connected with a sensor and comprises a data acquisition and input unit, a first control unit, a data storage device and a second control unit, wherein the data acquisition and input unit comprises a first passage and a second passage which are connected with the sensor, the first control unit is used for comparing acquired data with a preset signal amplitude trigger threshold value so as to capture effective waveform data, and the effective waveform data is written in the datastorage device, the data storage device comprises a first storage module and a second storage module, and the second control unit is used for reading the effective waveform data captured by the firstcontrol unit from the data storage device and inputting the effective waveform data to a storage device. By the lightning arrester, the discharging current measurement accuracy of the lightning arrester is favorably improved.