Abstract: The application of small radius curved bridges in urban interchange ramp bridges and mountainous bridges is becoming increasingly common, thanks to their beautiful design and excellent adaptability to complex terrain. Among them, the concave island type variable pier height curved bridge is widely used in mountainous areas due to its ability to adapt to undulating terrain. However, previous earthquake disasters have shown that its irregular spatial structural characteristics make its mechanical characteristics exceptionally complex under earthquake action, resulting in severe damage. This article takes a concave island type variable pier height curved box girder bridge as the research background. Based on SAP2000 finite element software, a nonlinear analysis model of the concave island type variable pier height curved bridge is established. The finite element model is modified and optimized using vibration table test data to study the influence of different support arrangements on its seismic performance. Research has found that a reasonable arrangement of supports is crucial for the seismic performance of structures. The use of unidirectional sliding bearings for low piers can reduce displacement and internal force response under earthquake action, while the use of pier beam consolidation for high piers can more effectively control the overall displacement of the main beam and reduce the risk of damage compared to fixed bearings. Further analysis shows that the arrangement of middle pier supports has a significant impact on the structural stress. Fixed supports can better constrain the horizontal displacement of the middle pier compared to radial sliding supports, allocate internal forces reasonably, and improve seismic resistance. The results show that the arrangement of high piers with pier beam consolidation, middle piers with fixed bearings, and low piers with radial and tangential unconstrained unidirectional sliding bearings can effectively improve the stress performance of concave island shaped variable pier high curve bridges.