The multi-phase supergene karst have developed with multi-plane of unconformity in Tazhong area of the Lower-Middle Ordovician Yingshan Formation that mainly went through the middle Caledonian-early Hercynian tectonic movements，but the dominated factors affecting the distribution characteristics of supergene karst were not analyzed deeply enough at the moment. In the study area the Lower-Middle Ordovician is a set of stable platform deposition. The karst palaeogeomorphology of the Yingshan Formation was recovered using isochronous residual thickness and was divided into three geomorphic units as karst highland，karst slope and karst basin. Combining with the cave-depth analysis of the supergene karst in Tarim，the depth of supergene karst in the study area is within 180 meters below the unconformity. Karst layers were identified through integrating drilling，core，log and seismic data. It is found that 3 karst platform surfaces are corresponding to 3 karst layers based on the karst layer comparative analysis in the study area，and the karst layers mainly developed in the karst slopes. The main factors affecting karst distribution are lithologic and structure.