The C12-C16 olefin fractions were separated by distillation from coal chemical mixed olefins. The obtained C12-C16 olefins were used as raw materials to synthesize polyalphaolefin (PAO) by AlCl3 catalyst. The influence of polymerization temperature, polymerization time, polymerization pressure and amount of catalyst were researched. The optimum polymerization conditions were determined. The physical properties of the product were analyzed. The results show that the evaporation temperature of C12-C16 olefins in cold trap oil is 214~274 ℃. Under the conditions of polymerization temperature of 137 ℃, polymerization time of 40 min, polymerization pressure of 4.0 MPa and catalyst mass of 10 g, the polymerization yield is 84.57%, and the kinematic viscosity of obtained PAO product at 40 ℃ is 32.53 mm2/s, the flash point is 221 ℃, the freezing point is -53 ℃, and the bromine value is 9.6 g(Br)/(100 g) .