Terahertztechnologyhasbeendevelopedrapidly overthepastfewdecades.Asapowerfultoolforcharactering biomacromolecules, terahertz spectroscopy and imaging technologies have been demonstrated their broad prospects in diagnostic and clinical medicine. The specific components of biological samples can be quantitatively analyzed by a terahertzspectroscopy, andsimilarly, thespatialdistributionofthecomponentsmeasuredinsamples canbedetectedwith terahertzimagingsystems.Thispaperreviewssomerepresentativeinthefieldsofterahertzdiagnosticmedicinebasedonthe types of terahertz optical systems, some investigations on terahertz biological effects are introduced from the level of biologicalindividuals, tissues, cells, andbiologicalmacromolecules.Althoughthisfieldisstillinthetrialandpreliminary explorationstage, therearemanypioneeringresearcheswithgreatpotentialhavebeenproposed, suchasterahertz-assisted targeteddrugtransmembranetransportandterahertzcancercellDNAdemethylation.Finally, theresearchstatusofterahertz biologicaleffectsissummarizedandthekeydirectionsandpossiblebreakthroughsinthisfieldareanalyzedandprospected.