This invention provides a long-chain linear α-olefin and its preparation method. The preparation method includes the following steps: Step 1,
ethylene is subjected to oligomerization reaction under the action of a main catalyst, a co-catalyst, and a
chain transfer agent; Step 2, after the oligomerization reaction in Step 1 is completed, the reaction mixture is mixed with a chain eliminator to carry out a chain
elimination reaction, and then the chain
elimination reaction is terminated to obtain a long-chain linear α-olefin; wherein the
chain transfer agent is
diethylzinc and / or diethylmagnesium. In the preparation method of the long-chain linear α-olefin of this invention, the
ethylene polymerization activity is high, the α-olefin selectivity is high, the linear selectivity is high, and the oligomerization product is C8-C9. 30 The method yields linear α-olefins. Furthermore, the oligomers obtained by this invention have a narrow distribution, and the
product distribution is not a Schulz-Flory distribution but follows a Poisson distribution. Therefore, the yield of long-chain linear α-olefins is higher, and the long-chain C... 12 ~C 20 The selectivity for linear α-olefins with a
carbon number of up to 85 mol% can be achieved.