Observation of fratcure morphology and energy spectrum analysis of fracture toughness specimens of high strength aluminum alloy was carried out on scanning electron microscope (SEM), and the fracture behaviour of this alloy has also been studied. It is revealed that the fracture surface can be divided into 3 regions: precrack region, propagation region and rapid fracture region, the appearance of which is similar to that of cleavage fracture, mixed mode fracture and static fracture, respectively. The fracture of high strength aluminum alloy is primarily influenced by coarsed Fe-rich particles which is relatively brittle, and the major fracture mode of this kind of alloy is toughness fracture casued by coarsed second phase particles.