Based on the experimental data of K(P) measured in this paper, the thermodynamic calculation of K(P) from K(f) and equation of state was studied and it was found that the chemical equilibrium of methanol synthesis can be described well by using Cherednichenko (1963)＇s K(f, CO) and Bissett (1977)＇s K(f, RS) relationship sad a modified SRK equation. Meanwhile, the equilibrium constant K(f) it methanol synthesis in literature since 1930s were appraised. It was found that the obvious deviations of K(f) values of different authors would be given because of different basic thermochemical data and the accumulations of the deviations.