In order to study the rheology of fatty acid ionic liquids with different structures and its effect on the properties of lubricating oil,three environmentally friendly lubricants were prepared from ricinoleic acid,oleic acid,dimer acid and choline,including（[cho] [ricinoleat]，[cho] [oleat]，[cho] [dimer]）.Their rheological and tribological properties were investigated by Rheometer and SRV.The lubrication mechanism was preliminary explored by analyzing the worn surfaces with SEM/EDS.The results show that both[cho] [ricinoleate] and[cho] [dimer] are ionic liquids and in liquid state at room temperature,but [cho] [oleate] is semisolid and seems like a lubricant grease.The viscosities of [cho] [ricinoleate] and [cho] [dimer] are always higher than that of 150BS base oil with the changes of temperature and shearing rate.Especially,\[cho\]\[dimer\] with the highest viscosity shows the optimal friction reducing and anti-wear properties.The probable reason is speculated that [cho] [dimer] as an ionic liquid forms an adsorption film with double electric layer,and its highest viscosity increases the lubrication film thickness and loading capacity.