Abstract: A wide-range thick-bedded oolitic limestone of Zhangxia Formation is exposed in Yanzibu area, which provides material for the study of paleo-ocean environment in Northern Jiangsu Province. The petrological and geochemical characteristics of oolitic limestone in the Lower Zhangxia Formation were analyzed by field observation, microscopic identification and geochemical test. The results show that the oolitic limestone in the study area is mainly composed of oolitic and bright crystal calcite cements. The distribution characteristics of trace elements and REE are consistent, indicating that the marine environment remained relatively stable during the depositional period of Zhangxia Formation. The geochemical characteristics of oolitic limestone were weakly affected by terrigenous contamination and diagenesis, which can be used for paleoenvironmental restoration. Based on the discriminant indexes of geochemistry and petrology, the authors concluded that oolitic limestone in the Lower Zhangxia Formation in the study area was formed in high-energy epicontinental sedimentary environment, which is hot, dry, evaporative and oxidized, which could provide an important basis for the restoration of Cambrian paleoenvironment in Northern Jiangsu Province.