Abstract: In this paper, the samples are collected from Majiagou-514 sub-member in Jingbian area and analyzed by scanning electronic microscopy (SEM), casting thin section and mercury penetration. The category and feature of pores in carbonate reservoir dominated by dissolved and intercrystal pores are presented. The reservoir property has been obviously improved by the paleokarst process. Its genetic process of secondary pores can be divided into the meteoric water controlled karst phase and the buried condition controlled solution phase.

Key words: Ordos basin, carbonate rocr, reservoir, pore evolution