The thermodynamic properties of a liquid are generally determined from an equation of state (EOS) through isothermal integration. Kahl (1967. Physical Review, 155, 78-80) and Nitsche (1992. Fluid Phase Equilibria, 78, 157-190) both questioned the validity of performing isothermal integration on a liquid and devised a Kahl's integration path to obtain liquid properties. In this paper, an alternate approach to revise the isothermal integration on liquid was presented. A temperature-dependent revision factor alpha>(*) over bar * (T) was introduced to the liquid fugacity coefficient expression derived from traditional isothermal integration, and the vapor pressure of pure liquids can be reproduced. In er;tension to mixtures, since the vapor-liquid equilibrium (VLE) has been taken into account by the revision factor alpha>(*) over bar * (T), simple mixing rules are adequate for EOS parameters even for highly non-ideal systems. Two types of mixing rule have been developed for a(T) depend on the VLE complexity. The proposed revision method and its application were illustrated through a modified Redlich-Kwong (MRK) EOS aiming at improving the description of volumetric properties. The test results on the VLE and PVT behavior of 43 pure substances and 17 binary mixtures are impressive. The comparisons with the widely used Soave-Redlich-Kwong and Peng-Robinson equations of state indicate the advantages of the proposed revision method and the superiority of MRK EOS.