Based on a liquid phase decomposition reaction, WO3 − x nanorods with different dimensions were synthesized by varying the organic acid to amine ratio in the solvent. By manipulating the acid to amine ratio, the nanorods with the length ranging from 20 to 59 nm were synthesized. Through the deconvolution of the visible and near-infrared spectrum into localized surface plasmon resonance (LSPR) absorption and small polaron hopping absorption, it was revealed that the latter dominated as the length of WO3 − x nanorods increased. The nanorods with tunable optical absorption characteristic were applied in solar control PVB films which showed improved near-infrared (NIR) shielding performance.