Keywords: 
• V_p/V_a ratio /
• Decollement structure /
• Deep-seated fault /
• 2-D density inversion /

Abstract: Based on the eighth Five-Year-Plan period research results of composite geophysical deep sounding in Xingtai seismic area, the interpretation of Pwave and S wave, 2-D density inversion, shallow structures and 3-D numerical simulation of stress field are combined to research comprehensively, and the seismogenic process of Xingtai seismic area is revealed with the example of 1966 Xingtai M 6.8 earthquake. In Xingtai seismic area, the deep structure and media feature are as follows:①There are high angle deep-seated faults in NE direction in the middle and lower crust and there is an apparent anomaly of V_p/V_a ratio in both sides of the deep-seated faults. ②There are low velocity and high conduction layer and the heterogenous anomaly of density in the middle crust. ③There are decollement structures in the bottom of the upper crust and Shulu fault depression is in the shallow.