Abstract: Six kinds of water-soluble polyether ester were prepared and their tribological properties used as an additive in water were evaluated on a four-ball tester. The effects of alkyl chain and the molecular weight of polyethylene glycol on the water-solubility and the tribology property of the additives were studied in detail. The results showed that , in the polyether estermolecular structure, the length of the alkyl chain and the molecular weight of polyethylene glycol had influences on the tribology property and the water solubility, respectively. In practice, a reasonable choice of alkyl chain length and the length of polyoxyethylene should be made to compromise the tribological properties and water-soluble of the additives.