Abstract: Several 7A04 aluminum alloy forging stocks were found to have fractured in the production process. In this paper, macro and micro observation on the fracture surface, energy spectrum analysis, metallurgical structure examination were carried out to analyze the failure mode and cause. The fracture surfaces was also compared with man-made fracture surfaces. The results show that there is a mass of inclusions on the fracture surface, which mainly consis of iron oxide, along with little magnesium oxide and aluminium oxide. The formation of inclusions are rich in iron oxide may attrihutes to the foreign iron oxide droped in the melt, which was enveloped by oxidation film.