o study the lateral failure mechanism and elastic-plastic performance of inverted Y-shaped concrete towers for long span bridges under strong earthquake, the Sutong Bridge was taken as a prototype and its finite element model was established using OpenSees platform. According to the equivalent principle of dynamic characteristics and the internal forces of key sections under dead loads, the full-scale bridge model was simplified to be a single-tower model. Meanwhile, time-history analyses were conducted to determine the displacement-based two-point load pattern. Then, a 1:35 scale specimen of the simplified single-tower was constructed to perform a quasi-static pushover test using the displacement-based two-point load pattern. Finally, based on the test results and numerical analyses, the yielding order and failure positions as well as the inelastic performance of the concrete tower in the transverse direction were obtained. The results show that the simplified single-tower model can be used to represent the full-scale bridge model for the study of lateral seismic failure mechanism. Under lateral strong earthquakes, the column section above the crossbeam firstly yields, followed by the bottom section of the tower and then the column section below the crossbeam. The failure position of the concrete tower can be the column section above the crossbeam or the bottom section of the tower. A large post-yielding strength of the tower was observed, whereas the failure displacement can be 4~6 times of the yielding displacement. It is also found in this study that the increase of transverse reinforcement ratio can obviously improve the global strength and displacement capacity of the tower.