Abstract: On the basis of observation data of several seismic sounding profiles and model data of multiple profiles section,this paper presents depth contour of the crystalline basement and that of Moho discontinuity of the Capital area,studies the deep crust velocity structure and the tectonic of this area.The deep crust velocity structure and tectonic show strong lateral heterogeneity,shallow basement faults develops well.The Moho surface contour shows the general characteristics of gradual deepening trend from east to west.The highest gradient zone is near Pinggu and Tangshan area in where deep crustal fault zone may exist with low velocity body along the fault zone.