The anchoring of platinum quantum dots (Pt QDs) on the surface of hematite (α-Fe2O3) nanorods is regarded as an efficient way to promote photoelectrochemical activity. To further improve the performance of the Pt-hematite material system, the size and location of the Pt QDs is a key factor to be considered. In this work, an α-Fe2O3 nanorod array film was grown on a transparent conductive FTO substrate by a facile hydrothermal method. Pt QDs with a diameter of ∼2 nm were uniformly deposited on the surface of the α-Fe2O3 nanorod. The dispersibility of the Pt QDs was greatly improved by regulating the surface wettability of the α-Fe2O3 thin film. The dependence of surface wettability on the micro-/nano-structure of the α-Fe2O3 array was revealed. Due to the structure regulation of the α-Fe2O3 nanoarray and the greatly improved dispersibility of the Pt QDs, the photocurrent of the 2.7 wt% Pt QD anchored α-Fe2O3 nanorod array was ten times higher than that of the pure α-Fe2O3 nanorod array. This work points to an efficient approach for dispersing the QDs in a nanoarray thin film by adjusting its micro-/nano-structure and surface wettability.