The intensity of future earthquake is unpredictable.The tower in transverse direction of cable- stayedbridge may act in a nonlinear way in ultra- fortified earthquakes.In this paper,by taking a long- span cable- stayedbridge as the research object,a finite element model is established to analyze the transverse seismic response of ca-ble- stayed bridge under the action of strong earthquake.Then,the seismic capacity- to- demand ratio is introduced tojudge whether the crossbeam is yielding.Moreover,a fiber section beam element is employed to simulate the ine-lastic behavior of crossbeam,and the influence of crossbeam yielding on the transverse seismic response of cable-stayed bridge is finally investigated in detail.The results show that (1) as the seismic capacity- to- demand ratio ofcable- stayed bridge crossbeam is relatively small,a ductility design for crossbeam may be more reasonable; (2) theseismic axial force of crossbeam changes significantly,which may greatly affect the yielding moment; and (3) asthe yielded crossbeam greatly affects the transverse seismic response of cable- stayed bridge,the increasing bendingmoment of tower base should be considered in the design process.