Abstract: Based on a simplified analytical model for the reinforced concrete side retainer, in the background of a continuous girder bridge with different pier heights, comparative research was conducted on two typical simplified seismic analytical methods (i.e., neglecting the side retainer and taking the transverse connection between girder and pier to be fixed) through IDA. The results show that using different seismic analytical methods, similar trends can be found in the distribution of transverse inertial force, which indicates that thelarger the height is, the larger shear force can be expected in the pier. However, the shear force discrepancy between the tallest pier and the shortest pier can be several times different when different seismic analytical methods are adopted. Distribution of the transverse shear force among the piers becomes much more uneven as PGA increases regardless of the seismic analytical method applied. It is appropriate to select a reasonable simplified analytical method according to the strength of the retainer and the intensity of the earthquake. When the strength of the retainer is large and the ground motion is relatively small (PGA≤0.8g), the aforementioned two simplified analytical methods cannot be adopted to calculate the shear demand as well as the plastic level of the shorter piers, where the mechanical characteristics of the retainer should be taken into consideration.