The oolitic beachs are widely distributed in the southern Ordos Basin during the Cambrian Zhangxia Formation sedimentary period. However, controlling factors of reservoir are not known, only industrial gas flow have seen in a few wells. The reservoir of the Zhangxia Formations is not a relatively simple beach reservoir, and the degree of reservoir development may be controlled by other factors. Methods: In this paper, the analysis of petrography and geochemistry of new drilling wells and field profiles are utilized to dissect the developmental characteristics of the Zhangxia Formation reservoirs, and then reveal the main controlling factors of the Zhangxia Formation reservoirs.Results: ① The reservoir rocks of the Zhangxia Formation are mainly (residual) oolitic—grainstone dolostone and fine—medium crystallined dolostone, and there are vug, fractures, and enlarged dissolution pores and intergranular pores in the reservoir space. ② The thickness of dolostone of the Zhangxia Formation varies greatly in the southern Ordos Basin, showing the characteristics of “more in the upper section, less in the lower section, more in the south, less in the north”. The dolostone has coarser, relatively authomorphic crystals, carbon, oxygen and strontium isotope values similar to those of seawater, similar rare earth element distribution patterns with seawater, and high strontium content; the fracture- filled dolomite has a saddle structure, with slight Eu anomalies. Dolomitization occurred mainly in the shallow burial period, and the dolomitization fluid is mainly seawater.Conclusions: The Zhangxia Formation in the periphery of the Zhenyuan paleouplift in the southern part of the Ordos Basin is strongly influenced by the karst of the Huaiyuan Movement and the Caledonian Movement—Hercynian Movement. Far away from the Zhenyuan paleo- uplift area, the reservoirs are mainly influenced by the fracture activities of the Huaiyuan Movement.