The bismuth sulfide (Bi2S3) nanoribbons with different length-to-width ratio are successfully prepared using a simple solvothermal technique. Their crystal structures, morphologies, as well as the optical absorption are characterized by powder X-ray diffraction, transmission electron microscope, UV-vis diffuse-reflection spectroscopy and nitrogen adsorption. The electron microscopy observation shows that the molar ratio of Bi and S source greatly influences the size of the as-prepared Bi2S3 nanoribbons and, thereby, the length-to-width ratio. The Bi2S3 nanocatalysts with the largest length-to-width ratio exhibits the highest activity for photocatalytic reduction of CO2 into methanol because it has the most negative potential of conduction band, the largest BET specific surface area and lowest recombination of photogenerated charge carriers. (C) 2016 Elsevier B.V. All rights reserved.