Banded iron formations (BIFs) were mainly formed in the early Precambrian (3.8~1.8Ga); they record some important information about the evolution of early Earth and contain very large amounts of iron ores. This paper summarizes the significant advances and open issues on the BIF related studies in China and abroad: ① the statistics and comparisons indicate that the BIF deposition was associated with momentous geological events, such as mantle plumes and crustal growth; ② the REE and Nd isotope show that Fe precipitated from marine seawater with minor high temperature hydrothermal component in the proportion of 1:1000; ③ most of BIFs have no Ce anomalies with enrichment in δ57FeIRMM, implying that the paleo ocean was in low abundances of O2 and thus Fe2+ could not be oxidized; ④ some key scientific problems have not been resolved, such as the source of Si, precipitation mechanism and genesis of bands; ⑤ BIFs in the North China Craton primarily occurred at about 2.54 Ga; however, some issues need to research deeply, such as the BIF types, formation ages and genesis of high grade iron ores. We propose that the comparative studies on typical BIFs and applications of advanced measuring techniques are helpful to understand the precise procedures of BIF deposition and early evolution of old cratons.