To address the catalyst recovery issue in traditional photocatalysis processes, photocatalytic membrane reactors have emerged as a novel technology in recent years. However, the understanding of the differences in photocatalytic performance and mechanism between the membrane and slurry systems is missing. The current study provided a comprehensive comparison between the photocatalytic slurry system (CN-P) and membrane system (CN-M) in terms of bisphenol A (BPA) degradation and mineralization, in which the well-developed g-C₃N₄ was chosen as the catalyst. The fabrication of CN-M was optimized via tuning initial urea concentration, and a series of characterization technologies confirmed the successful incorporation of g-C₃N₄ onto the membrane. Different reaction mechanisms were proposed in two systems via the identification of contributed reactive species and the degradation products. The “sea anemone effect” in the membrane system enhanced the mass transfer between the reactive species and the BPA molecules and promoted the BPA mineralization with less toxic intermediates. Furthermore, the CN-M exhibited excellent anti-fouling and self-cleaning properties with a much lower irreversible fouling resistance than the original membrane and could be regenerated rapidly after visible light irradiation. These findings provided new insights for the CN-M system as a promising and reliable alternative to the traditional photocatalytic process, which is of great significance and importance in promoting the practical application of photocatalytic membranes in water treatment.