LiNi0.5Co0.2Mn0.3O2（NCM） cathode material samples with D50 at 7.7 μm（NCM-S） and 19.9 μm（NCM-B） were synthe sized by solid state method using lithium carbonate and nickel cobalt manganese hydroxide precursor as raw materials.A se ries of samples were obtained by blending the above two materials according to NCM-B mass fraction in the range of 20%~ 90%.Physical and electrochemical properties of these samples were analyzed and tested by laser particle size analyzer，tap den sity meter，SEM and battery test equipment.Compared with NCM-B sample，the tap density of NCM-80% increased to 2.96 g/cm3 from 2.90 g/cm3.The initial capacity raised to 178.6 mA·h/g from 176.3 mA·h/g，and the capacity retention of 100th cycles raised to 92.7% from 91.9%.These results can be attributed to the infilling effect of small particles into the voids of big particles with close packing，which improves the conductive network of active materials and increases energy density of batteries.