The coking kerosene fraction was used as the raw material for the experiment. The linear α?olefins in the raw oil were enriched by complex extraction method, and the high viscosity poly α?olefin base oil (PAO) was synthesized by oligomerization. The effects of temperature, time and catalyst dosage on the properties of PAO were investigated. The kinematic viscosity, viscosity index and PAO yield rate at 100 ℃ were determined. Under the optimum process conditions of catalyst mass fraction of 6%, polymerization temperature of 25 °C, polymerization time of 8.0 h, addition polymerization temperature of 80 °C and addition polymerization time of 2.0 h, the reaction effect is the best: The kinematic viscosity of PAO at 100 ℃ is 43.54 mm²/s, the viscosit index is 163, the freezing point is -50 ℃, and the flash point is 291 ℃. The yield is 85.48%. Compared with the PAO40 standard, the obtained product is a high viscosity lube base oil.