The present disclosure provides a method of separating α-olefin by a simulated moving bed. The method comprises using a coal-based Fischer-Tropsch synthetic oil as a raw material to obtain a target olefin having a carbon number N within a range from 9 to 18, wherein the raw material is subjected to treatment steps including pretreatment, fraction cutting, alkane-alkene separation, and isomer separation, thereby obtaining a high purity α-olefin product. As compared to conventional rectification and extraction processes, the product obtained by the method of the present disclosure has advantages of higher purity, higher yield, lower energy consumption, and significantly reduced production cost.