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The analysis of metallographic structure is one of the important methods for lightning disaster investigation. The metallographic structure analysis is made of different metal materials that had been impacted by simulate lightning currents, with emphasis on the influence of lightning current impulses on the metal materials through changing microstructure. The results show that the metallographic structure of the metal materials changed obviously after impacted by simulated lightning currents. The metallographic structure changes for different metal material are different obviously. For the same metal material impacted by lightning currents, the amplitude of metallographic structure change is in inverse proportion to the sectional area.