The theoretical calculation of stable isotope fractionation is an important aspect of both stable isotopic theory and mineral's thermodynamic research because it deals with mineral's property in both microscope and macroscope. Many models have been proposed since Urey(1947)and most of them are based on the change in free energy and calculated from the reduced partition function ratios. Two trendecies have been displayed in recent models:simplication-getting reasonable results with less index;accuratif ication-characterized by the widely used of computer and the complicated thermodynamic calculation. With the developement in this area，the theoretical calculation could become an important way to understand mineral's isotopic fractionation properties in future.