Rationally designing and constructing high-efficiency composite photocatalysts with advantaged structure play significant roles in efficient photoelectrochemical or photocatalytic solar energy conversion systems. In this work, contrasted to the typical CdS nanoparticles modified TiO2 nanomaterials, a novel rods-on-rods CdS branched TiO2 nanoarrays have been firstly synthesized by a simple in-situ growth strategy. The controllable surface-to-volume ratios of CdS nanorods, combining with their original intimate connection with TiO2 nanorods, not only enhance both the solar light scattering and absorption performance, but also effectively promote the separation and transportation of photogenerated charges. In addition, this structure ensures adequate exposure of CdS to the electrolyte, thus increasing the photooxidation reactive sites. In a typical photoelectrochemical water splitting system, the maximum photon-to-current conversion efficiency reaches 34% under 450 nm wavelength light irradiation, and the best applied bias photo to current conversion efficiency of the samples runs up to 1.5% under solar light irradiation. Interestingly, by using a 'cocatalysts-separated-loading' strategy, the novel CdS branched TiO2 nanoarrays films can be further employed as self-bias photocatalytic films, which also obtain an enhanced photocatalytic hydrogen production activity and stability.