Abstract: From the results of precursory generality, relevant theoretieal analysis and roek test, the seience and reasonableness of thesource一hardening model are diseussed in this paper.It is pointed out that the source of strong earthquake experiences four stages of elastie deformation, media hardening,fraeturing nueleation and in stabilizing.The distur-bance range of source stress and strain is only half of the source size,which can not affeetseveral hundred km away,but at least 500 km for Preeursory anomaly before a M7 earth-quake.Therefore,the preeursory anomalies and earthquakes are all the results and ex-pressions of aetion of regional stress fields.The precursory anomalies are the results of fissure,deformation and displaeement generating from shallow roek body around the ob-servational points.The earthquakes are the results of quick fraeture of roeks around the Source areas.Their oeeurrenees in the same field are not the reciProeal eausation.The hardening of media round source is the main cause generating quiescence of moderate and small shoeks within the source areas in the medium and short stages,non –preeursory anomaly,seismic gaps,as well as precursory anomaly migrating from periphery to the Ceflter.

Key words: Hardeningmodel, Soureestress, Disturbaneerange, Non一soureeinforma-tion, Oeeurreneeinthesamefield