Culture experiments of carbonate mineral using Lagoa Vermelha improved medium with 6∶1 molar ratio of Mg/Ca within 100 days were conducted under the mediation of Clostridium sp. (SN-1 strain) isolated from sediments in the Qinghai Lake. At the same time, aseptic experiments were carried out as the control. Mineral species and morphologies were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results showed that: ① The quantities of sediments in bacterial culture experiments were always more than those in the control ones. ② The change trend of carbonate mineral assemblages formed in Clostridium sp. SN-1 strain culture was calcite → calcite and monohydrocalcite →monohydrocalcite and calcite →monohydrocalcite, while in the control experiments the change trend was monohydrocalcite and calcite→ calcite and monohydrocalcite; ③ Based on comprehensive analysis of SEM and XRD, the authors considered that dumbbell-shaped minerals might be high-magnesium calcite, while spherical minerals might be monohydrocalcite.