One-dimensional TiO₂ nanotube arrays have attracted tremendous interest due to their superior physical and chemical properties. However, one of the noteworthy drawbacks of them is the poor visible light utilization owing to their large energy gap. In order to effectively enhance their visible light absorption and boost up their photoelectrochemical performance, plasmonic Ag nanoparticles with specific size and uniform dispersion are selected and loaded on the surface of TiO₂ nanotubes. Up to now, the rational design and effective control of the morphology of Ag nanoparticles have rarely been achieved due to the intrinsic limitation of the traditional method. Herein, we have successfully reached the modulation of the dimension of Ag nanoparticles through a modified solvothermal method. It is found that the dimension and distribution of Ag nanoparticles play an important role on the photoelectrochemical performance of TiO₂ nanotube arrays. In particular, it has been proposed that only the Ag nanoparticles with suitable dimension and uniform distribution can greatly improve the photoelectric activities of TiO₂ due to its superior surface plasmon resonance under visible light. Additionally, the influence factors of Ag nanoparticles during the solvothermal process have also been discussed detailedly.