High selectively synthesis from syngas to ethanol is the important way to further improve the economic benefits in the underground coal gasification,ethanol as alternative to petroleum-derived fuels can help to solve the problem of our countrys increasingly serious environmental pollution and energy shortage.Experiment show that Rh exhibits good activity and selectivity to CO hydrogenation to ethanol,and introduction of Fe significantly increase the selectivity[1].To make it clear,we empolyed density functional theory and combined with cluster and slab models to reveal the complex mechanism[2].We firstly scrutinized the adsorption and dissociation of H2、CO and HCO on a series of Fe-Rh catalyst.Then we analyzed the kinetics and thermodynamincs of CO and CHx coupling to ethanol.Lastly our studies demostrate that the rate-limiting step of the overall conversion is the dissociation of HCO.The above results provide valuable information for optimizing the available hydrogenation catalysts and for designing new ones.