An end cross girder plays an important role when the steel girder bridge is subjected to seismic loading. But located near the girder end, it is often found corroded, which could degrade the load-carrying capacity. Therefore, it is of a practical significance to investigate the seismic performance of a corroded end cross girder. To this end, the present study conducts nonlinear finite element analysis of end cross girders with various corrosions under horizontal load. It is observed that the corrosion area and the plate-thickness loss influence the load-carrying capacity, and their influence depends on the corrosion type. It is also pointed out whether or not the lower flange is connected to the main girder makes a large difference in the load-carrying capacity: the connection between the lower flange and the main girder is therefore very important for seismic performance.