Abstract: In order to investigate the rotation response of two-span simply supported skewed girder bridges (TSSSGB) under bi-directional earthquake excitation, the software OpenSees was selected to build finite element models that the effects of longitudinal pounding between two decks, and transverse pounding between decks and retainers were considered. The influences of skew angle, number and layout of diaphragms, supporting stiffness of substructure and span layout on the rotation of TSSSGB were analyzed from two viewpoints:the modal characteristics and the seismic responses. The results show that the rotation vibration mode of simply supported skewed girder bridges appears earlier than that of right bridges. The increase of skew angle intensifies the rotation of TSSSGB. The low order vibration modes of asymmetric structures have shown translational and rotational coupling vibration, and its structural eccentric effect intensifies the rotation of TSSSGB. The rotation of TSSSGB can be intensified without or setting too much diaphragms, or setting diaphragms oriented parallel to support skew. The effects of longitudinal pounding between two decks on the rotation of TSSSGB are different for different skew angles, and transverse retainers can effectively restrain the rotation of each deck.