Abstract: The tribological properties of benzotriazole and its derivatives as additives in rapeseed oil were investigated using a four ball machine. The morphologies and chemical features of the worn steel surfaces were observed and examined by means of X ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). As the results, benzotriazole as an additive increase the antiwear ability of the base stock to some extent but has no effect on the extreme pressure properties, while the derivative with long chain alkyl decreases the antiwear ability of the base stock though it has better solubility therein. SEM observation of the worn steel surface and XPS examination of the chemical states of N on the worn surface indicate that a surface protective film was formed on the worn surface, by way of chemisorption and/or tribochemical reaction. The wear of SAE52100 steel under the lubrication of rapeseed oil and rapeseed oil containing benzotriazole derivatives is characterized by scuffing.