Abstract: The modification effects of K2CO3 on β-Mo2C catalysts for mixed alcohols synthesis from CO hydrogenation were studied. Un-prompted β-Mo2C produced mainly hydrocarbons of C1-C4 under the reaction conditions of 573 K, 8.0 MPa, H2/CO=1.0, GHSV=2 000 h－1. Addition of K2CO3 to β-Mo2C resulted in remarkable selectivity shift from hydrocarbons to alcohols. Moreover, the promoter of potassium enhanced the ability of chain propagation of β-Mo2C with the higher selectivity of C2+ alcohols. The investigations of the loadings of K2CO3 in β-Mo2C revealed that the maximum of alcohol yield obtained at K/Mo (molar ratio) =0.2. On K/β-Mo2C catalysts, the distribution of hydrocarbons obeyed the traditional linear Anderson-Schultz-Flory equation, while the distribution of alcohols gave a unique linear Anderson-Schultz-Flory with remarkable deviation of methanol. Thus, potassium promoter exerted a prominent function on the whole chain propagation to produce alcohols especially for the stage of methanol to ethanol.