Based on aeromagnetic data,the author advances some opinions on the basement structure and relief of northern Ordos basin as well as the controlling role of the basement fault in the development of the basin,and makes description from characteristics of geophysical fields.Studies show that the southern part and western part of Ih Ju League constitute a deep depression.With Parker method,this paper has made combined calculation for gravity and magnetic data and determined the thickness and distribution of Cambrian Ordovician strata,thus providing grounds for oil and gas exploration at depth.The tectonic development of the basin and characteristics of the cover are also discussed.