A novel kind of MnCO3 nanoplatelets-reduced graphene oxide (RGO) composites, as an anode material in rechargeable Li-ion battery, was prepared by a simple low temperature reaction route. The graphene not only provided an avenue for the transport of Li-ion, but also buffered the volume expansion of MnCO3 nanoplatelets during charge and discharge. Compared to pure MnCO3 nanoplatelets, MnCO3-RGO composites presented the improved electrochemical performances. At a low current density of 100mAg−1, MnCO3-RGO composites delivered a desired performance of 849.1mAhg−1 after 200 cycles. When at a high current density of 500mAg−1, the discharge capacity still maintained at 810.9mAhg−1 after 700 cycles. Our experimental results suggest that this composite will be a candidate as a novel anode material for the power batteries of electric vehicles and the energy storage batteries of smart grids in the future.