A novel acetate-assisted antisolvent precipitation method combined with ball milling and heat treatment is developed to synthesize nanosized carbon-coated LiMnPO4 material. The precursor prepared by the precipitation process is composed of Mn3(PO4)2 and Li3PO4 nanoparticles. After heat treatment of the ball-milled mixture of precursor and glucose, the carbon-coated LiMnPO4 with the particle size of around 60 nm is obtained. The LiMnPO4 nanocomposite synthesized at the optimized conditions delivers specific discharge capacities of 154, 134, 120, 90, and 61 mAh g−1 at the rates of 0.05, 0.2, 1, 5, and 10C, respectively, which are comparable to some of the best reported C-LiMnPO4 materials prepared by other synthesis methods. This material further exhibits good cycling stability, especially at high discharge rates of 5C and 10C.