It is proved Gonghe basin is not low intensity zone by the 1990 Gonghe M_S7.0 earthquake and traces of palaeoearthquake in the basin.It's seismic risk should not be ignored.Based on a large number of studies,geologic background of the Gonghe earthquake is analysed and seismogenic process of the event is discussed.The result shows that development period of the event is about 20 years and can be divided into 4 stages,that is,long term,medium term,short term and impending term,reflecting the process from elastic deformation,ductile deformation,harding strain to precursory creep of crustal medium.