An accurate knowledge about phase behaviors of CH4,CO2 and their binary mixture is crucial in fields of natural gas liquefaction and refrigeration applications.In this work,two all-atom force fields of Tra PPE-EH and EMP2 were used for the components CH4 and CO2,respectively.Then the vapor-liquid equilibria(VLE)of CH4,CO2 and their binary system were calculated via the NVT-and Np T Gibbs Ensemble Monte Carlo Simulations.Meanwhile the traditional method using Equation of State(Eo S)to correlate the VLE properties was also investigated.The Eo Ss considered in this work were three classic cubic RK,SRK,PR and another advanced molecular-based PC-SAFT equations.For pure components,both molecular simulations and the PC-SAFT Eo S could obtain satisfactory predictions for all the saturated properties.However,the saturated liquid densities calculated by the cubic Eo Ss were not so good.It was also observed that the Tra PPE-EH force field had a good representation for CH4 molecule,while the EMP2 force field was not enough accurate to represent CO2 molecules.For the mixture CH4+CO2,SRK and PR showed the best predictions for the saturated pressure-component property,while good results were also obtained via molecular simulations and PC-SAFT Eo S.It was suggested that special combining rules or binary interaction parameters were important to obtain enough accurate prediction of the mixed phase behavior.Compared with the cubic Eo S,the PC-SAFT and molecular simulation method showed better adaptabilities for both the pure and mixture systems.Besides,the accurate molecular parameters used in the PC-SAFT and molecular simulations could bring about direct and deep understanding about the molecular characteristics. An accurate knowledge about phase behaviors of CH4, CO2 and their binary mixture is crucial in fields of natural gas liquefaction and refrigeration applications. This work, two all-atom force fields of Tra PPE-EH and EMP2 were used for the components CH4 and CO2, respectively. The vapor-liquid equilibria (VLE) of CH4, CO2 and their binary system were calculated via the NVT-and Np T Gibbs Ensemble Monte Carlo Simulations. While the traditional method using Equation of State (Eo S) to correlate the VLE properties were also investigated. The Eo Ss considered in this work were three classic cubic RK, SRK, PR and another advanced molecular-based PC-SAFT equations. For pure components, both molecular simulations and the PC-SAFT Eo S could be obtained satisfactory predictions for all the saturated properties. However, the saturated liquid densities calculated by the cubic Eo Ss were not so good. It was also observed that the Tra PPE-EH force field had a good representation for the CH4 molecule, while the EMP2 force field was not enough accurate to represent CO2 molecules. For the mixture CH4 + CO2, SRK and PR showed the best predictions for the saturated pressure-component property, while good results were also obtained via molecular simulations and PC-SAFT Eo S. It was suggested that special combining rules or binary interaction parameters were important to obtain enough accurate prediction of the mixed phase behavior. Compared with the cubic Eo S, the PC-SAFT and molecular simulation method showed better adaptabilities for both the pure and mixture systems .esides , the accurate molecular parameters used in the PC-SAFT and molecular simulations could bring about direct and deep understanding about the molecular characteristics.