Soil vapor extraction (SVE) as an emerging in-situ remediation technology has been applied to remove subsurface pollut ion of petroleum chemicals all over the world.Although the technology has found more and more application, theoretical invest igations to improve its designs and practices should continue systematically.For contaminants and fluid mediums in SVE, there exist different types of transfers, conversions and physicochemical behaviors because of the complicated multiphase system of gas-water-oil(NAPL)-solid.To make certain these processes, interdisciplinary approaches should be employed.In this paper, a basic mathematical model of SVE is presented according to the dynamic theory of fluids in porous media and the transition theory in chemical engineering with some applied assumptions.Some momentum equations, mass conservation equations and NAPL depletion equations aimed at describing SVE processes have been derived.