To study the mechanism of material particle size effects on the electrochemical properties of LiNi0.5Co0.2Mn0.3O2, two kinds of materials with particle size of 300nm and 1μm were prepared, based on the electrospinning method and sol-gel method, respectively. The capacity differences of the two materials at 20mA/g discharge current were unapparent, in the potential range of 2.8V–4.3V, but become gigantic at 1000mA/g discharge current. Electrochemical impedance spectroscopy (EIS) was employed to analysis the differences caused by particle size, and frequency responses of every electrochemical process were analyzed in detail through Bode plots, which proved the electrospinning material had an excellent performance caused by a shorter lithium ion and electron diffusion distance.