The Ordovician Yingshan karst reservoirs are of great petroleum potential in Tazhong Northern Slope, Tarim Basin. Further petroleum exploration needs to know more accurate spacial distribution of the karst reservoirs. According to reflection characteristics of 3D seismic data, it is shown that a serial of karstification have undergone in the upper part of Yingshan Formation, which is a diagenetic process from denudation through coexisting denudation and karstification to karstification and then filling. Erosional truncation happened in structural highs as water tables rose during every karstification. A multiphase development model of Yingshan karst reservoirs is proposed.