Abstract: In order to further study the dynamic fracture process of beryllium aluminum alloy, the tensile process of powder metallurgy beryllium aluminum alloy was observed through scanning electron microscopy and its fracture mechanism was analyzed. The results show that the original structure of beryllium aluminum alloy is mainly A1 phase which shows a network structure, and the Be phase is discretely distributed in the middle of A1 phase. When the tensile stress reaches 170 MPa, the structure of the beryllium aluminum alloy does not change significantly; when the tensile stress reaches 190 MPa, the microcrack of the Be phase begins to appear in the structure of beryllium aluminum alloy. As the stress increases, the crack expands along the interface between the Be and Al phases. When the stress reaches 215 MPa, the specimen is unstable and fractured. It is known that the cracks of beryllium aluminum alloy originate from the Be phase during the stretching process,but it mainly fractures at the interface between the Be and Al phases or the Al phase.