A simple one-step electrochemical deposition method was demonstrated to fabricate reduced graphene oxide/Ag nanoparticle co-decorated TiO2 nanotube arrays (RGO/Ag-TiO2NTs) photocatalyst in this study. The structures and properties of these photocatalysts were characterized using scanning electron microscope, X-ray diffraction, UV-Vis diffuse reflection spectra, and photoluminescence. By taking the advantages of TiO2, graphene, and Ag nanoparticles (AgNPs), RGO/Ag-TiO2NTs showed a greatly improved photocatalytic activity compared with the bare TiO2NTs, Ag-TiO2NTs or RGO-TiO2NTs. The deposited RGO and AgNPs not only reduce the recombination of photogenerated electrons and holes, but also increase the surface area of the catalyst. Both photocatalytic performance and adsorptivity of the catalyst have been improved. The ternary photocatalyst exhibited over 93 % removal efficiency of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) under simulated solar light irradiation with good stability and easy recovery, which justifies the photocatalytic system, a promising application for herbicide or other organic pollutant removal from water.