Abstract: The barium resources is very rich in Qinba area, Shaanxi Province, with 3 ore belts, that is South (Zhenba-Chengkou), Middle (Luohe-Zhuxi) and North Belts (Cigou-Chiai). The middle barite ore belt is located and spreaded along the south margin of Pingli Dome (Pt₃) that was developed in the Ankang Eopalaeozoic rift (O-S), and its strata belong to the Ziyang-Pingli Partion. The barite deposit is hosted Upper Sinian Dengying Formation, which is a set of dolomite, dolomitic limestone, siliceous rock and carbonaceous siliceous slate. The output characteristics of barite ore-layer have an important coupling relationship with regional tectonic and sedimentary environment. The trough depression at the south margin of Pingli paleo-land was a semi-closed oceanic basin, the volcano (clastic) rock basement structure provides a rich Ba,S source for mineralization. When the seawater solution evaluated from acidic to weak acid-alkalescent oxidation environment, the barite was deposited as mineral deposit. Therefore, this deposit belongs to the sedimentary barite deposit in shallow-water trench that was related to submarine volcano (sedimentary) activities.