A method for utilizing the C4
raffinate to prepare the olefin of the invention belongs to the technical field of olefin preparation. In order to solve the problem that the C4
raffinate can not be sufficiently utilized, the invention proposes that the C4
raffinate is first pre-separated so as to remove the
propane, the propylene and the isobutene in the C4 raffinate and then the treated C4 raffinate is delivered to an olefin catalytic
cracking system, and the generated
cracking gas mixtures go into a cooling
system to be cooled down and then are compressed with entering a compression section; the compressed catalytic
cracking gas goes into an absorption
tower and the light components such as the
methane, the C2, etc. are produced from the top of the absorption
tower and the column bottom matters flow through a
separation system with being separated so as to respectively obtain the C3 components, the C4 components and the C5 components and heavier components with the C5 and heavier components as absorbents. The combined process of the invention has the advantages of sufficient utilization of the C4 raffinate, few
hydrogen circulations, low
energy consumption, high propylene yield, simple operation, low investment, etc.