In order to systematically investigate the failure mechanism of oil pipeline bridges under the combined action of earthquakes and foundation deformations, a refined finite element analysis model for oil pipeline bridges was established in this study. By combining the seismic time-history analysis method and the step-by-step simulation method of foundation deformation, the variation laws of various responses of oil pipeline bridges under the action of earthquakes, foundation deformations and their combined action were systematically investigated. On this basis, the disaster mitigation effects of different seismic isolation bearings were compared. The results show that due to the relatively low transverse stiffness of the oil pipeline bridge, the transverse responses of the pipeline bridge structure are much larger than the longitudinal responses under the action of earthquakes, foundation deformations and their combined action, and almost all bearings are damaged. Under the action of foundation deformations alone, excessive foundation displacement will lead to the displacement of pier structures and the damage of pipeline bridge structures. The adoption of seismic isolation bearings can effectively reduce various dynamic responses of the structure, decrease the damage risk by more than 60% and significantly improve the disaster resistance capacity of pipeline bridge. Lead rubber bearing and high-damping rubber bearing exhibit good disaster mitigation effects under the action of earthquakes and foundation deformations, and their comprehensive disaster reduction efficiency is 25% to 40% higher than that of ordinary rubber bearings. The disaster mitigation design ideas and data results proposed in this study can provide data support and theoretical reference for the optimization of disaster resistance design of oil pipeline bridges.