The space distribution characteristics of structures from topography and landform of the south part of Ordos block and Weihe basin are analyzed.It is considered that three dimensional cross structures are formed by three NW upwarpings of the south part of Ordos block and EW subsidence centers which range obliquely as well as cross uplifts among them in Weihe basin.The space distribution of historical and modern earthquakes in and surrounding the Weihe basin shows that three dimensional cross structures have a strong dominion on seismicity in the basin.