A series of LiMnxFey(V▯)1-x-yPO4 samples have been synthesized as cathode materials for lithium-ion batteries. The structure and electrochemical performance of the samples are investigated systematically. All the modified samples show improved performance compared to the pristine LiMnPO4. Moreover, the four LiMnxFey(V▯)1-x-yPO4 samples (x=1/3, y=1/3; x=0.5, y=0.2; x=0.5, y=0.3 and x=0.5, y=0.4) exhibit enhanced electrochemical properties than LiMn0.5Fe0.5PO4. Among them, LiMn1/3Fe1/3(V▯)1/3PO4 delivers the highest initial capacity of 161 mAh·g−1 at 0.05C and still retains 143 mAh·g−1 after 50 cycles at 0.5C with capacity retention of 98.6%. In addition, the calcination temperature is important for V3+ doping into the olivine structure, and our results clearly indicate that the sample calcined at 600°C performs better electrochemical performance than that at 500°C.