Abstract: Aiming at the issue that little research is conducted on reservoir porous media absorbing fluids，oil phases(condensated oil and crude oil)is regarded as multicomponent liquid hydrocarbon macromolecular solution，based on the excessive absorption，the UNIFAC method is used to determine the activity coefficient of each component in the solution，by introducing the testing equation(GibbsDuhem equation)of phase equilibrim thermodynamic consistency，combined with the existing same fugacity between absorption phase and bulk phase while absorption getting equilibrim，as well as the relational expressions，the general expression of mathematic model of equilibrim state absorption can be obtained，meanwhile，considering mass transfering among phases and the process reaching phase equilibrim not instantaneously，the component mode related to time is introduced，so as to obtainthe mathematic model of nonequilibrim absorption.

Key words: oil phase, porous media, nonequilibrim, adsorption, mathematic model