Molar-tooth carbonates are intricately crumpled, microsparry calcite fissure fills formed during the Mesoproterozoic-Neoproterozoic. This article studied the sedimentary environment, petrological characteristics and age limit of distribution of molar-tooth carbonates in the Xuzhou-Huainan Area, and discussed its origin. Molar-tooth carbonates mostly occur in micritic limestone, marls, calcisilicic micrite, micrites and marls bearing silt in strata of the Xuzhou-Huainan area. The petrological characteristics of molar-tooth carbonates indicate their formation and development in a sedimentary system of slow ramp in a stable craton, and represent a shallow-water environment of subtide. According to their relationship with neighboring rocks, molar-tooth carbonates are divided into four types, perpendicular, handing-over, disorderly and parallel, and six types of combination types. The classification has an environmental implication and reflects respectively different carbonate sedimentary environments. Based on the cycle sequences and the microfacies units of the molar-tooth types, microfacies environment diagrams of the molar-tooth carbonate types are established. Neoproterozoic molar-tooth carbonates of this area are composed of microsparite calcite of homogenous, uniform, equal-axial and polygonal forms obviously different from its surrounding matrix in composition, texture and mineralogy. The formation of the molar-tooth carbonates needs rapid lithification not observed in modern subtide environments, and would seem, to require higher level of CaCO3 supersaturation than that in today's oceans. They developed during 850- 720 Ma and disappeared before the Sturtian glaciation in the Xuzhou-Huainan area. Molar-tooth carbonates disappeared suddenly before 700 Ma because the Sturtian glaciation changed the chemistry of the oceans. A decrease in CaCO3 saturation and increase in the concentration of precipitation in the mid-Neoproterozoic seawater might have contributed to the disappearance of molar-tooth carbonates.