In this work, the excellent visible-light-response Ag/AgCl photocatalyst was prepared on cotton fabric using polydopamine (PDA) as adhesive agent and reducing agent through chemical self-polymerization and reductionoxidation reaction. The introduction of PDA was beneficial for reducing Ag+ and bonding the Ag/AgCl photocatalyst on the cotton fabric. The fabrics played an important role in supporting photocatalysts and accelerating the adsorption of pollutants. Results showed that the Ag/AgCl photocatalysts were uniformly loaded on the surface of cotton fibers due to the influence of PDA. The cotton(C)/PDA/Ag/AgCl photocatalysts displayed an outstanding photocatalytic activity with 95% of C.I. RB 19 dye degradegation rate within 180 min. Its degradation rate constant was approximately 31 times higher than those of pure cotton, C/PDA and C/PDA/Ag. And O-center dot(2)- and h(+) were confirmed to be the active species in the photo-degradation process according to the free radical and holes scavenging experiment. Based on the above research results, the flexible C/PDA/Ag/AgCl composite photocatalytic fabric would have great advantages in dye wastewater field due to its outstanding photocatalytic activity and recyclability.