Abstract: Hydrogen energy is regarded as the most promising clean energy in the 21st century due to its advantages of clean,efficient and renewable.Water-gas shift (WGS) reaction is a commonly employed reaction in the industry.It is also an important means of hydrogen production while recycling CO waste gas.Besides,it has the dual advantages of environmental governance and energy saving and emission reduction.As a catalyst support,α-MOC shows excellent properties.Pd,Ni and Pt based catalysts are commonly used in the WGS reaction.In order to further understand the role of α-MoC support in the WGS reaction and its catalytic performance under different metal loadings,the reaction mechanism and activities of Ni4/α-MoC (111),Pd4/α-MoC (111) and Pt4/α-MoC (111) were investigated by using density function theory (DFT) and kinetic Monte Carlo (KMC) simulation.The results show that the WGS reaction on Ni4/α-MoC (111) and Pd4/α-MoC (111) is redox mechanism,of which *CO combines with atomic oxygen from water decomposition to generate CO2;the WGS reaction on Pt4/α-MoC (111) occurs via the carboxyl pathway,of which carboxylate intermediate is formation from *CO reacts with *OH produced from water decomposition.Ni4/α-MoC (111) and Pd4/α-MoC (111) show low catalytic activity because of the high energy barrier.At a low temperature,Pt4/α-MoC (111) also shows low a catalytic activity due to strong stability of *CO,of which the active sites are covered by *CO.With the reaction temperature increasing,the desorption energy of *CO decreases,and the catalytic activity increases.At the reaction temperature varied from 400 to 500 K,Pt4/α-MoC (111) shows the highest H2 turnover frequency at 1 atm with a CO:H2O ratio of 1.Compared with the Pt/Al2O3 and Pt/TiO2,Pt/α-MoC shows the highest H2 turnover frequency.