In order to increase the filling ratio of CdS photosensitized layer into the TiO₂ array, a low-density TiO₂ nanorod array with short-length rods and large rod-interval is prepared based on the TiO₂ seed layer-coated FTO conductive glass through hydrothermal process. CdS seed layer is covered onto the TiO₂ nanorod by chemical bath deposition. Then CdS photosensitized layer is grown in the TiO₂ nanorod array via hydrothermal approach. SEM, XRD, UV-Vis absorption spectra are employed to characterize the TiO₂/CdS composite films with different hydrothermal time of CdS. The photoelectrochemical properties of the TiO₂/CdS composite film are also studied. The results indicate that the low-density of the TiO₂ nanorod array could facilitate the infiltration of the CdS growth solution into the TiO₂ array to form the perfect coverage with CdS seed layers. CdS photosensitized layers are homogeneously grown on the whole TiO₂ nanorods and gradually filled in the TiO₂ array through hydrothermal process. Meanwhile, flower-like CdS modified layers composed with short-length rods are formed at the top of composite film array. The light absorption of the TiO₂ nanorod array is extended to the visible region with the CdS modification. The photocurrent of the TiO₂/CdS composite film is obtained via 7 h hydrothermal growth of CdS layer. The excellent photoelctrochemical performance of the composite film of CdS modified TiO₂ nanorod array with low density reveales its application prospect in solar cells.