The single-pillar pier bent cap is widely used in municipal bridge engineering and even sea-crossing bridge projects because of its small area occupation, large clearance and good landscape effect. However, due to the use of single-pillar pier, the transversal dimensions of the piers are relatively large. The influence of the piers on the stress of bent cap should be considered during the analysis of the bent cap stress. Taking the Shenzhong Channel Project as the background, various calculation models are used to calculate the stress on the wide pier single-pillar bent cap of substructure at the its approach bridge of flood discharge area in detail. The safety of various models to the design and the influence of wide pier on the stress of bent cap are compared and analyzed so as to put forward some suggestions on the design and calculation of bent cap.