The magnetotelluric sounding results show that electrical structure is simple inside Ordos block and complex in the arcuate fault zones on the western border of the block.In the arcuate fault zones,lateral change of conductivity is severe and the low resistivity layer in upper mantle tends to deepen.This is different from Yinchuan fault basin where upper mantle structure is uplifted.It is considered that tectonics are tensional in the Yinchuan basin and compressional in the arcuate fault zones.In addition,deep electrical structure is uplifted between Daluoshan and Huianpu.It is shown that this is a deep-seated fault where the North-South tectonic belt passes through.