In this study, a series of phase-pure LiMn1-xFexPO4/C (x=0.2, 0.4, 0.6) cathode materials were successfully synthesized by solid-state method. The structure, particle size, surface morphology and electrochemical properties of these cathode active materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical model cell and cyclic voltammograms (CV). The results indicated that the different atom ratio of Mn/Fe affected its electrochemical preformance. A lithium battery using LiMn0.6Fe0.4PO4 as the active materials of the positive electrode exhibits a high initial charge capacity and discharge capacity of 141.5 mAh g-1 and 125.7 mAh g-1, respectively, and the initial coulombic efficiency is 88.8％. After 25 cycles, it retains 99.8% of the initial discharge capacity at 0.2C rate, showing perfect cyclic property.