The Tonian Period (1000–720 Ma) witnessed the transition from a prokaryote-dominated marine ecosystem to one that was characterized by proliferation of eukaryotes, and this fundamental shift has been interpreted as reflecting the rise of eukaryotic algae driven by increasing nutrient availability, e.g., phosphate and nitrate, in the mid-Tonian. Uranium isotope measurements from carbonate rocks indicate an extensive shallow water anoxia in the early Tonian oceans, just prior to or coincident with this marine ecosystem transition in Tonian. The Huainan and Feishui groups crop out in the southeastern margin of North China craton, detrital zircon ages and biostratigraphic data indicate that they are early Tonian in age, and thus provide suitable material for revealing this marine ecosystem transition and associated paleoenvironmental changes. We carried out iron speciation, inorganic and organic carbon isotope, and sulfur isotope analyses for the Huainan and Feishui groups in Huainan area of northern Anhui Province. The carbon isotope profile provides an additional chemostratigraphic evidence for early Tonian age of the Liulaobei Formation of the Huainan Group. Iron speciation data, with most of the FeHR/FeT values less than 0.2, reveal a persistent oxic bottom water conditions, apparently inconsistent with an extensive shallow water anoxia scenario indicated by uranium isotope data. The present study may suggest a heterogeneous ocean redox state in early Tonian, and indicates that availability of nitrate and phosphate may have already started to increase in early Tonian and accordingly led to diversification of eukaryotes.