Abstract: With the deepening standards and requirements of zero wastewater discharge, efficient and sustainable membrane separation water treatment technology has become a research hotspot, but faces problems such as low water flux and easy pollution. In this work, photocatalytic self-cleaning composite membranes were prepared by the organic combination of graphitic carbon nitride (g-C₃N₄), bacterial cellulose (BC) and bismuth sulfide (Bi₂S₃) by vacuum-assisted filtration. The effects of different additions of g-C₃N₄ and Bi₂S₃ on the dye separation performance of the composite membranes were investigated through a series of characterization methods to analyze the physical structure and elemental energy states of the powders and membrane materials, and the degradation mechanism of the dyes under photocatalysis were explored. The results show that 60wt%g-C₃N₄, 10wt%BC, 30wt%Bi₂S₃ and the composite membrane have the best overall performance, with the water flux and rejection rate of 23.48 L·m⁻²·h⁻¹ and 100%, respectively. The water flux of 16.65 L·m⁻²·h⁻¹ and dye rejection rate of about 90% are still maintained in the long term filtration. The flux recovery rate reach 96.5% after soaking for 3 h under light, indicating that the membrane has good photocatalytic self-cleaning performance. This paper provides new ideas and basic exploration for the design of high-throughput and sustainable separation membranes.