ZnO nanorod/TiO2 nanoparticle composite films were prepared by a sol-gel method, in which the slurry of TiO2 nanoparticles (NPs) were penetrated into ZnO nanorod arrays. The agglomerate size of TiO2 NPs was controlled with tetraethylammonium hydroxide. Lowering ZnO nanorod array density was an effective way to fill TiO2 NPs in the space of ZnO nanorod array. The presence of ZnO and TiO2 was confirmed by scanning electron microscopy and X-ray diffraction. Triblock copolymer (P123) was added as a template agent to obtain high specific surface area, and the solar cell performance was improved. However, the viscosity of the TiO2 slurry was increased by addition of P123, and TiO2 content in the composite film was reduced. Low concentration TiO2 slurry was preferable to be penetrated into ZnO nanorod array and solar cell performance was further improved.