Abstract: The cathode materials LiNi_0.5Mn_0.3Co_0.2O₂ were synthesized through high -temperature calcination mixed with the compound of lithium carbonate and cobalt nickel manganese hydroxide precursor, which prepared by liquid co-precipitation technique. The effect of Al(OH)₃ doped material on cycling performance was studied. The prepared powders were characterized by powder X-ray diffraction, scanning electron microscope, and electro-chemical character of the material was studied by electric performance testing instrument. It was proved that the material calcinated at 850 ℃ showed the best performance, the first discharge capacity of 2.75~4.2 V and at 1 C was 157.2 mAh/g, the capacity retention ratio was 94.8 % after 50 cycles and 90.1 % after 100 cycles. Through a small amount of Al doping, the crystalline of the material was improved and the crystal type tended to be complete while the discharge capacity decreased. There is no obvious influence on the material's cycle stability at the former 100 cycles.