Abstract: Qualitative simulation experiments were used to prepare the primary short circuit melted marks on copper wires. The microstructure changes of the primary short circuit melted marks under different heating conditions were studied using methods such as metallographic examination, hardness testing and scanning electron microscopy analysis. The results show that the copper wire was continuously heated after the formation of primary short circuit melted mark, and the microstructure exhibited recrystallization phenomenon. When the heating temperature of the melt was 800 ℃ and the holding time was 100 minutes, all cellular crystals transformed into columnar crystals.