Prefabricated Vertical Drain (PVD) is a vertical channel of water discharge in foundation treated by drainage and consolidation. As the large settlement caused by foundation treatment results in the deflection of PVD, the corresponding decrease of flow capacity and reinforcement effect caused by the deflection of PVD should be studied. By building fixed iron frame model, PVDs were bended artificially to simulate the bending deformation in real working condition. On this basis, the water discharge capacities of four representative PVDs (conventional type with separated filtration fabrics, anti-silting type with separated filtration fabrics, conventional type with integral filtration fabrics, and anti-silting type with integral filtration fabrics) in different bending conditions were compared. Results indicate that conventional integral drainage board has the best drainage performance in the same bending form, followed by that of anti-silting integral type, filter-separated anti-silting type, and filter-separated conventional type. Core veneer, filtration fabric and bending angle are main factors influencing the flow capacity of PVD.