Nano-WS2 (tungsten disulfide nanoparticles) lubricating oil additive, prepared by the nanometer WS2 particulates and semi-synthetic engine base oil as raw materials, was added into Great Wall engine oil with different mass ratio. With a contrast study on these oil samples, the results show that it can improve the extreme pressure, antiwear and viscosity-temperature properties of the engine oil effectively by adding a certain amount of nano-WS2 additive, and the optimal concentration is 2wt%. The oil film strength, sintering load and viscosity index of this lubricating oil is respectively 1.35 times, 1.58 times and 1.05 times as that of Great Wall engine oil. In addition, when tested under the grinding conditions of 392 N, 1450 r /min and 30 min, the diameter of worn spot reduces 0.018mm, and the average friction coefficients of friction pairs decrease 16.3%, both of which are lubricated by the oil containing nano-WS2 additive. Meanwhile, the experiments testify that the tribological and viscosity-temperature properties of the nano-WS2 additive are better than that of the Henkel MoS2 additive.