Abstract: Under scanning electron microscopic observation,micro-pores and micro-fractures in the carbonate reservoirs of Sub-sinian formation of the Reqiu oil field are classified into the following types: 1.primary micro-pores consisting of intercrystalline micro-pores and intra-algae micro-pores. 2.secondary pores(solution pores)consisting of pores with fillings and pores without fillings;and 3.fractures consisting of diagenetic fractures,tectonic fractures and solution fractures. The formation under review is well developed with pores and fractures which are interconnected.It has very good reservoir property and is highly productive.