Abstract: From analyses of six new drilling wells抍ores, sidewall coring, rock thin section and imaging logging data, the dissolved pores,intergranular pores, structural fractures and dissolved fissures are the main reservoir spaces of the carbonate reservoirs of Ordovician Yingshan formation in Gucheng low swell in Tarim basin, and the major reservoirs of Yingshan formation are dominated by heterogeneous fractures and vugs. The complex pore origins, including early meteoric water leaching, dolomitization, hydrothermal modification after crude oil charging, result in the strong heterogeneity of them by both constructive dissolution and destructive filling effect. It is the ancient landform highland of lower member of Yingshan formation that cut fault?communicating hydrotherm at the basement, modifies the pre?existing porous and permeable zones ranging from hundreds to thousands meters, and controls the distribution of relatively high quality reservoirs by the early meteoric water leaching effect followed by dolomitization. Seismic prediction of the reservoirs shows that the large?scale and effective reservoirs could be found in the ancient landform highland, the superimposed belts between dolomite and basement?cutting faults in west?central Gucheng low swell