The increase of atmospheric oxygen fugacity has a significant impact on the geochemical cycling of Fe isotopes, which may be recorded in the Precambrian Banded Iron Formation. This paper studied Fe isotope compositions and major elements of the Neoproterozoic BIF from the Sanjiang area, Guangxi Province. The Fe isotopic compositions of the Neoproterozoic BIF were analyzed using MSICPMC. Relative to the reference material IRMM014, the iron isotope composition of bulk samples range from 1.60 to 2.20 , with an average of 1.85 . The results show BIF samples are enriched in Fe heavy isotopes. The δ57Fe value between the dark and light bands has the difference of 0.4‰, which was caused by terrestrial debris input. Without the impact of debris, the δ57Fe of hematite from the seawater precipitate is 2‰, indicating that surface water was suboxic, even lower than the Archean. This shows that the ice still covers the most of ocean in Fulu period, only partial melting. This suggests that the ice covered most of ocean in Fulu period, only partial melting. Therefore, the Fulu period is the relatively warm phase of the glacial age, rather than the interglacial stage.