LiMnBO3 and its carbon-coated composite (LiMnBO3/C) were prepared by a rheological phase reaction method. Citric acid was used as the carbon source during the synthesis process. The structure and morphology of samples were characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The effects of the carbon coating and the annealing temperature on the structure and electrochemical properties have also been investigated. According to the electrochemical tests, the carbon-coated LiMnBO3 showed greatly improved specific discharge capacity, rate capability, and cycling stability due to the improved electrical conductivity. The carbon-coated sample (LiMnBO3/C) annealed at 750 °C exhibited better performance than that of the bare LiMnBO3. (The composite electrode had a reversible specific discharge capacity of about 172 mAh g-1 at 10 mA g-1, and the capacity retention was 82.9% after 50 cycles, whereas the bare LiMnBO3 had an initial specific discharge capacity of 87.7 mAhg-1). These results indicate that the carbon-coated LiMnBO3/C could be a promising cathode material for lithium ion batteries.