The invention relates to a reaction method for preparing low carbon olefins from CO hydrogenation. The problem that the selectivity of a catalyst in the process of preparing olefins from synthesis gasis low is mainly solved. The reaction method for preparing the low carbon olefins from CO hydrogenation includes the step that synthesis gas and a catalyst are subjected to a contact reaction to generate the low carbon olefins, wherein the catalyst is prepared from, by weight, 30%-70% of Mo-containing active components and 30%-70% of carriers in the technical scheme; the problem is well solved, and the reaction method can be used for industrial application of preparing the low carbon olefins from the synthesis gas.