Abstract: The integrated experimental system of material evidence for fire trace was used to make residues of aluminum wire under different overcurrents.The fracture morphology of the wire was observed and analyzed by the scanning electron microscopy.The results show that with the increase of overcurrent the cup-cone fracture becomes larger, and the the dimple also becomes larger. Therefore, scanning electron microscopy can be used to observe and analyze the character of the fracture morphology of aluminum wire and identify whether or not it is overloaded and the degree of overload.