The zinc oxide (ZnO) arrester DC parameter tester is a specialized testing device used to detect moisture，aging，valve plate degradation，and internal defects in ZnO arresters. A systematic calibration method is proposed for the leakage current parameters of ZnO arresters at 1 mA DC reference voltage (U_1mA) and at 0.75U_1mA. Experimental and application results demonstrate that this calibration method is accurate and reliable，effectively enabling the traceability of the tester's measurement values and providing technical support for the safe operation of power equipment.