Abstract: In the condensate oil and gas recovery process, components and contents of oil and gas change constantly and thermo-physical properties such as enthalpy, entropy, viscosity and specific heat also change accordingly. To correctly calculate these dynamic parameters, a phase equilibrium calculation model for oil and gas is given. This model consists of material equilibrium condition equation set, thermodynamic equilibrium condition equation set and state equation structure system and is resolved using VC++ language programming. PR state equation of actual gas is used to calculate phase equilibrium feature of a oil and gas component at three condensing temperatures such as 4 ℃, -50 ℃ and -110 ℃. The feature is closed to calculation results of Aspen software, so it can be taken as the basis of follow-up process simulation calculation.