This paper presents the facile synthesis of two different morphologies of WS nanomaterials-WS hexagonal nanoplates and nanoflowers-by a sulfurization reaction. The phases and morphology of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The tribological performance of the two kinds of WS nanomaterials as additives in paraffin oil were measured using a UMT (Universal Mechanical Tester)-2 tribotester. The results demonstrated that the friction and wear performance of paraffin oil can be greatly improved with the addition of WS nanomaterials, and that the morphology and content of WS nanomaterials have a significant effect on the tribological properties of paraffin oil. The tribological performance of lubricating oil was best when the concentration of the WS nanomaterial additive was 0.5 wt %. Moreover, the paraffin oil with added WS nanoflowers exhibited better tribological properties than paraffin oil with added WS hexagonal nanoplates. The superior tribological properties of WS nanoflowers can be attributed to their special morphology, which contributes to the formation of a uniform tribo-film during the sliding process.