Abstract: The depth of Curie surface in North Henan is calculated by using the frequency domain inversion method and program of 3-D magnetic interface.Combined with the feature of geological structure and the data of deep seismic sounding,Causes and machenism of earthquakes in North Henan are discussed,the huge shear force and thermal stress produced by the upwelling of thermal matter between the uplift and subsidence area of the crust are two direct forces for earthquake occurrence;the gradient zone of Curie surface in Tangyin graben and Dongpu downfaulted block,i.e.the conjunction zone of high temperature blocks and low temperature blocks,is the tectonic base of earthquake occurrence.And some views are put forward about key monitoring of potential focal regions in North Henan.