The invention relates to a separation method for preparation of ethylene by using biomass ethyl alcohol, mainly for solving the problem that product separation technologies in preparation of ethylene through dehydration of ethyl alcohol less are hardly related in studies in the past and the problem how to improve the yield of ethylene, and especially the technical problems of simplifying the separation refining technologies of biomass ethylene, improving the yield of ethylene and lowering the energy consumption. The method adopts the technical scheme of combination of a single tower technology and a heavy component steam stripping distillation tower, crude ethylene enters an ethylene rectification tower, the heavy components are discharged by the kettle of the tower, light components containing ethylene are separated at the top of the tower, liquid ethylene product is extracted from the side of the upper part of the ethylene rectification tower, the heavy components discharged from the kettle of the tower enters the top of the stream stripping distillation tower, a vapor phase at the top of the tower returns back to the middle lower part of the ethylene rectification tower, and the heavy components are discharged from the bottom of the tower. The technical scheme well solves the above problems, and the separation method can be used in industrial production of ethylene through dehydration of ethyl alcohol.