Pushover analysis and time history analysis of steel-concrete composite rigid frame bridge which is composed of RC piers and steel-concrete composite beams was conducted in the bridge longitudinal and transverse directions using OpenSees, and the applicability of pushover analysis by the first modal load was discussed as well. Besides, a new pushover analysis method which can consider the contribution of higher modes of vibration was proposed, and the applicability of this method in composite rigid frame bridge transverse and longitude direction was also analyzed. On this basis, a reduction coefficient of elas-to-plastic demand curve which can consider the influence of bidirectional seismic excitations was proposed, and a new pushover analysis method to predict the largest displacement of composite rigid frame bridges under bi-directional seismic excitations was proposed as well. It is also confirmed that this method is conservative.