Abstract: Amine tungsten diisopropylphosphorodithioate (W-SPN) was prepared, purified and identified. Its tribological behaviours in trimethylolpropane ester (TMPE) were examined. The maximum non- seizure load (PB) of W- SPN is higher than that of amine molybdenum diisopropylphosphorodithioate (Mo-SPN) and molybdenum diisopropylphosphorodithioate (MoDDP). The antiwear property of W-SPN is similar to that of Mo-SPN, but a little poorer than those of Zinc di (2-ethylhexyl)-phosphorodithioate (ZDDP) and amine diisopropylphosphorodithioate (SPN). The friction reduction efficiency of W-SPN is quite good. The friction coefficient of W-SPN equals 0. 06 under the load range from 98 N to 784 N in four-ball tester, and it is lower than that of Mo-SPN or MoDDP under low speed of 1 mm/s in Bowden tester. W-SPN can also make the rubbing surfaces smoother. The compositions of the surface films on the tested specimens were analyzed by AES and XPS in this paper.