The chemical co-precipitation method was used to synthesize LiFePO4 by doping with Mg2+,Al3+,Ti4+,V5+,and Ni 2+,then the specific charge/discharge capacity of LiFePO4 was measured by stable-current charge/discharge method and the particle structure was examined by X-ray diffraction and Rietveld method. The results indicate that a small amount of metal ion doping can improve the discharge capacity of LiFePO4 to above 120 mAh/g at high current and keeping the capacity over 80% after 20 cycles when the charge/discharge rate is at 2C for Li1-xTixFePO4,Li1-xVxFePO4 and Li1-xNixFePO4,mainly due to the metal ion dopings in the form of solid solution and occupying the position of Lithium. The metal ion dopings change the distance and position between atoms in grains,resulting in the contraction of unit cells,the increase of average distance between Li-O atoms and the disengagement of Lithium ions.