Abstract: The soluble polyether has attracted more attention due to its excellent lubricating performance and environment-friendly properties. The lubricating characteristics of castor oil polyoxyethylene ether solution, e.g. film forming ability, friction-reducing, anti-wear and extreme pressure properties, were systematically investigated on the lubricating film measuring instrument, universal micro-tribotester and four-ball friction tester, respectively. The friction and wear mechanisms were analyzed by scanning electron microscopy and energy dispersive spectroscopy. The results show that the film forming ability of water was improved by mixing in castor oil polyoxyethylene ether. The effective lubricating film can be formed at the tribo-interface of steel/aluminum tribo-pair to reduce friction coefficient and improve anti-wear properties. The performance of the castor oil polyoxyethylene ether solution in friction reduction, anti-wear and extreme pressure was improved with the increasing solution concentration.