In this study, Ag-doped g-C3N4-TiO2 nanocomposite photocatalysts were deposited on the surface of cotton fabric by a simpleone-step hydrothermal method. The structure features of as-modified cotton fabric were examined by a series of characterizationtechniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD) spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS) andphotoluminescence spectroscopy (PL). The experimental results showed that highly dispersed Ag nanoparticles were dopedinto g-C3N4-TiO2 nanocomposites which were evenly coated on the fabric surface. The introduction of Ag nanoparticles intog-C3N4-TiO2 composites could significantly improve the photodegradation rate of methyl orange (MO) dye under visiblelight irradiation. Importantly, the doping site of Ag nanoparticles had a significant influence on the photocatalytic activityof Ag-doped g-C3N4-TiO2 nanocomposites. Compared with the g-C3N4-TiO2 coated cotton fabric, the Ag-doped g-C3N4-TiO2 coated cotton fabric displayed excellent photocatalytic properties for the photodegradation of MO dyes because of thenarrowed band gap and the faster separation and transfer of photoinduced charge carriers. The substrate of cotton fabric hadlittle influence on the active radicals produced by the Ag-doped g-C3N4-TiO2 nanocomposites. In addition, the as-modifiedcotton fabric exhibited good reusability and stability after five recycles for the photodegradation of MO dyes.