Abstract: To ensure effective seismic resilience evaluation for electrical systems, the electrical failures caused by deformation and displacement of substation equipment should be carefully considered. However, existing evaluation frameworks focus on the level of structural failure and cannot reveal the actual electrical performance. Taking an ultra-high voltage bypass switch as an example, this paper studies the basic structural performance and electrical performance of the equipment under earthquake actions, and analyzes various potential failure modes by considering different working conditions of the equipment. The probability of failure under multiple failure modes is calculated using incremental dynamic analysis, and it is found that ignoring the failure of electrical functions will significantly underestimate the failure risk of the equipment, and the electrical functional failure is mainly brought by the excessive relative displacement response among equipment. By combining different modes of structural failure and electrical functional failure, three evaluation combinations (i.e., low, medium, and high requirement) are defined, and earthquake vulnerability analysis is carried out. The results show that the seismic intensity can greatly influence the predominant failure mode. At a low intensity, only low-requirement evaluation is required; while at a high intensity, medium- or high-requirement evaluation should be chosen according to equipment safety demand.