Poly -alpha -olefin is one kind of important lubricants.The polymerization of 1-decene catalyzed by boron trifluoride catalyst was studied.The properties of the synthesized poly -alpha - olefin lubricant were investigated under various kinds of technological conditions, for example , reaction temperature , reaction pressure , reaction time , various kinds of initiator , mole ratio of the catalyst and promoter .The optimum condition for the synthesis of poly-alpha-olefin are as follows :the reaction temperature is 30 ℃, the reaction pressure is 0 .4 MPa , the reaction time is 3 hours, the initiator is butanol, and the mole ratio of the catalyst to the initiator is 2 .0.The components of poly -alpha -olefin lubricants were analyzed using gas chromatog raph.Under the optimum technological conditions, the conversion of 1-decene is 99.8%, the mass fraction of dimer is 2 .5 %, the mass fraction of trimer is 64 .5%, the mass fraction of tetramer is 27.5 %, and the mass fraction of pentamer is 5 .6 %.The proper ties of the poly -alpha -olefin oils w ere studied by kinematical viscometer and petrolic products distilling test instrument .The viscosity is 4.80 mm²/s and 23 .09 mm²/s at 100 ℃ and 40 ℃, respectively .The viscosity index is 132 , the freezing point is -60 ℃.