In order to investigate the roles of gas phase and liquid phase on the the isospin fractionation process respectively,the degree of isospin fractionation < (N/Z)n>b/<(N/Z)imf >b is measured by the saturated neutron-proton ratios of the nucleon emission (gas phase),(N/Z)n>b and fragment emission ,< (N/Z)imf>b (liquid phase ) in the intermediate energy heavy ion collisions. From the calculated results we found that the In order to investigate the roles of gas phase and liquid phase on the isospin fractionation process, the degree of isospin fractionation <(N / Z) n> b / <(N / Z) imf> b is measured by the saturated neutron -proton ratios of the nucleon emission (gas phase), (N / Z) n> b and fragment emission, <(N / Z) imf> b (liquid phase) in the intermediate energy heavy ion collisions. found that the