A new approach for dominating the channel form of the flexible MIL-53(Fe) was developed by using a surfactant-assisted modified method. The surfactant tetraethylammonium hydroxide (TEAOH) can control the channel form of MIL-53(Fe) for a “closed-pore” form, whereas the surfactant polyoxyethylene polyoxypropylene polyoxyethylene (P123) or polyvinyl alcohol (PVA) can dominate the channel form of MIL-53(Fe) for a “large-pore” form. The photocatalytic performance of MIL-53(Fe) with different channel forms was investigated through the degradation of rhodamine B (Rh B) in water under violet light irradiation. The results showed that MIL-53(Fe) with a “large-pore” form exhibited higher photocatalytic activity than that of MIL-53(Fe) with a “closed-pore” form. MIL-53(Fe)-PVA that exhibit the best photocatalytic activity degraded almost 100% Rh B in 90 minutes.