The invention relates to an olefin separation method which is characterized by comprising the following steps: a hydrocarbon raw material and cyclic hydrocarbons enter a feeding buffer tank together and a material discharged from the bottom of the tank enters a heavy-component separation tower to obtain heavy components with the number of carbon atoms being greater than or equal to 4; a refined hydrocarbon raw material obtained in the middle of the buffer tank is decompressed and then enters a cold tank for heat exchange, and cold energy of different temperature levels is provided for the cold tank; after heat exchange, the refined hydrocarbon raw material enters a reactor, the obtained dehydrogenation product is cooled and then enters the cold tank, and is cooled step by step with materials of different temperatures in the cold tank, and the obtained vapor-liquid mixed phase is fed to a liquid separation tank for vapor and liquid separation; the separated vapor phase is returned to the cold tank for re-condensation, step-by-step cooling is performed on product vapor with LNG refrigerants of different temperatures when the product vapor is cooled to -25 DEG C to -40 DEG C till heavy components with the number of carbon atoms being greater than or equal to 3 in the product vapor are all condensed, and residual tail gas is discharged; and the liquid phase separated from the liquid separation tank enters the cold tank for recovering cold energy and then is fed into a light-component separation tower and a rectifying tower in sequence to obtain a propylene product from the tower top of the rectifying tower.