Ordovician carbonate hydrocarbon reservoir spaces are mainly corroded cavities in the oft-com:office:smarttags" />Ordos Basin. The dissolve freckle of single chip as the research object, about 300 rock chips of more than 100 drilling wells are observed. The results show that the filling degree of cavity is distinctly zoning. The cavities in the eastern and western area are completely filled and pores disappear. Based on the Ordovician residual thickness graphs and cumulative thickness graphs which are from the top of Ordovician to different layers, the ancient tectonic faces of the top of Ordovician in different periods can be recovered. The analysis suggest that the regionalization of hole filling degree and the fillings type is mainly controlled by the ancient tectonic patterns.