Anti-corrosion benzotriazole ionic liquid (IL, BTAP₄₄₄₄) was synthesized by neutralizing 1H-benzotriazole (BTAH) with terabutylphosphonium hydroxide (P₄₄₄₄OH). The physicochemical and tribological properties of BTAP₄₄₄₄ were measured and the results indicated that it had good lubricating properties for steel/steel, steel/copper and steel/aluminum friction pairs in reducing the friction coefficient and wear volume, especially when it worked for the steel/copper friction pair both at room temperature (RT) and 100 °C. Good performances were also found in terms of its anti-corrosion ability, thermal and hydrolysis stability, and viscosity temperature characteristics compared with commercially available synthetic oil poly-alpha-olefin (PAO 10) and traditional IL 1-butyl-3-methyl imidazolium tetrafluoroborate (bmimBF₄). The designing purpose of BTAP₄₄₄₄ is to enhance the anti-corrosion ability of the IL lubricant attributed to the introduction of a nitrogen heterocyclic structure, 1H-benzotriazole, which is normally used as antirust and corrosion inhibitor in mechanical engineering. The corrosion test results confirm our assumption and BTAP₄₄₄₄ shows excellent anti-corrosion ability for all the used friction pairs including steel/steel, steel/copper and steel/aluminum contacts.