Abstract: The stress fields in two kinds of packaging structures on a Printed Circuit Board (PCB) under random vibration loading were analyzed based on finite element analysis (FEA) software ABAQUS. The properties of different packaging structures were compared. The results indicate that, under random vibration loading, the nearer the edge of PCB, the higher the stress. Under the same conditions, the stress in PBGA was higher than that in QFP. For the same kind of packaging, the components whose stress were at least 10% lower than the maximum stress were non-weak components, and the others were weak components. According to this definition, QFP-1 and QFP-5 are weak components for 5 sets of QFP, while PBGA-3 is non-weak component for 5 sets of PBGA.