In this work, seven amino acid ionic liquids (AAILs) were synthesized and used as lubricating additives for water. The experimental results revealed that the friction coefficient and wear were reduced after the addition of an AAIL. Among them, the designed P4444-Trp AAIL not only exhibited excellent tribological properties but also possessed excellent antibacterial properties and low toxicity to plants. Based on the results of the mechanism analysis, we speculate that a boundary lubricant film containing polar elements, P and N, was formed on the surface of the steel-steel friction pair, and the excellent tribological properties were obtained through the synergistic effect of P and N. The synthesized ionic liquid can promote improvements in the environmental impact of water-based lubricating additives.