AfterreviewingtheanalyticaltheoriesofT-Scurve,somemethodsofT-Srelationship,andfuzzysetsforstudyingwatermasses,newmethodsoffittingthemembershipfunctionofoceanicwatermassesarepresentedbasedonthecharacteristicsofT-Scurvefamilyofoceanicwatermasses.ThemembershipfunctionsofoceanicSubsurfaceWaterMasswithhighsalinityandIntermediateWaterMasswithlowsalinityarefittedanddiscussedusingthenewmethods.Theproposedmethodsareusefulinanalyzingthemixingandmodifyingprocessesofthesewatermasses,especiallyintracingtheirsources.Theprinciplesandformulaeofthenewmethodsandexamplesaregiven.