The In₂S₃/(Pt-TiO₂) nanocomposite photocatalyst consisting of floriated In₂S₃ decorated with TiO₂ nanoparticles was synthesized by a multi-step method, which was used for the hydrogen production under visible-light (λ ≥ 420 nm) irradiation. The obtained In₂S₃/(Pt-TiO₂) nanocomposite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance absorption spectra (DRS), and photoluminescence spectra (PL). It is found that the Pt-TiO₂nanoparticles embedded in the interstices of the floriated In₂S₃ formed intimate contacts between the In₂S₃ and Pt-TiO₂, which is a benefit to significantly enhance the charge separation and then the photocatalytic activity. The effects of the mass ratio in the In₂S₃/(Pt-TiO₂) nanocomposites and Pt-loaded amount on the photoactivity for the hydrogen production were investigated comparatively. The results show that the In₂S₃/(Pt-TiO₂) nanocomposite with a mass ratio of 3 : 2 has the maximum photocatalytic hydrogen production rate of 135 μmol h⁻¹ under visible-light irradiation, and the possible mechanism of the obtained In₂S₃/(Pt-TiO₂) nanocomposite as a photocatalyst for hydrogen production was proposed.