Banded iron formations (BIFs) are common chemical sedimentary rocks in Precambrian strata. Neoproterozoic BIFs were mainly deposited at Cryogenian period (~717–635 Ma). Many scholars argued that the emergence of Neoproterozoic BIF is closely linked to the "Snowball Earth" event, but the causal relationship between them remains poorly understood. The Jiangkou BIF in the South China Block is a typical Neoproterozoic BIF. The Jiangkou iron ores are dominated by quartz, hematite and magnetite, followed by minor chlorite and carbonate minerals, which is characterized by the features of chemical sedimentary rocks. The studied BIF show high TFe2O3 and SiO2 contents, followed by Al2O3, CaO and MgO. Other elements, such as TiO2, MnO, Na2O, K2O, P2O5, high field strength elements and total rare earth elements (REE) are relatively low. Moreover, the Jiangkou BIF show significant positive correlations between Al?O? and TiO?, Zr, while there are moderate positive correlations between K?O and Al?O?, TiO?. All samples show low Y/Ho ratios (average of 29.2). When normalized to Post Archean Australian Shale (PAAS), all BIF samples show enrichment of high REE patterns relative to low REE patterns (LaPAAS/YbPAAS = 0.22~0.59) and positive Eu anomalies (Eu/Eu*=1.02~1.40). Comprehensively, we argued that iron was sourced from hydrothermal fluids and seawater. Furthermore, significant terrigenous clastic materials have been incorporated into Jiangkou BIF. The positve iron isotope values in Jiangkou BIF and the absence of significant negative Ce anomalies suggest that Jiangkou BIF was deposited in a suboxic to anoxic conditions. Combining with previous studies, we suggest that widespread anoxic and ferruginous oceans prevailed during the Cryogenian period. The oxygen released from meltwaters of localized glaciers could have triggered iron precipitation and leading to the formation of BIF.