A fast precipitation method is adopted for synthesis of nano-MnPO4·H2O, with MnSO4·H2O, H3PO4, NH4NO3 and NaOH as raw materials. MnPO4·H2O precipitate is characterized by XRD (X-ray diffraction) and SEM (scanning electron microscope). Fine-sized, well-crystallized, carbon-coated LiMnPO4/C nano-composites are obtained by using mechanochemical activation assisted carbothermal reduction route from as-prepared MnPO4·H2O, Li2CO3 and PVA (polyvinyl alcohol). The effect of calcination temperature on the structure and properties of obtained materials is investigated by XRD, SEM, TEM (transmission electron microscopy) and electrochemical measurements. The in situ 6.8wt% carbon coated LiMnPO4/C displays discharge specific capacity of 124mAhg−1 at 0.05C rate and 108mAhg−1 at 1C rate. The capacity retention is nearly 100% after 20 cycles at 1C rate. This mechanochemical activation assisted precipitation technique is a facile approach for the fabrication of LiMnPO4 cathode materials.