The invention relates to a method and a device for producing propylene and C4 hydrocarbons from an oxygen-containing compound. 80 wt% or more of C5 or more hydrocarbons in a product are cycled to a catalytic cracking riser, and undergo a cracking reaction to generate a product containing propylene and the C4 hydrocarbons. The method and the device increase the alkylation reaction rate of ethylene,and make the productivity per unit volume of a reactor high.