Due to the presence of graphite flake cascades,the real graphite anode of Li-ion battery shows non-isotropic characteristic. The present work developed an ellipsoid-based simulated annealing method and numerically reconstructed the three-dimensional microstructure of a graphite anode. The reconstructed anode is a composite of three clearly distinguished phases: pore(or electrolyte),graphite, and solid additives, well representing the nonisotropic heterogeneous characteristic of real graphite anode. Characterization analysis of the reconstructed electrode gives information such as the connectivity of individual phase, the specific interfacial area between solid and pore phase, and the pore size distribution. The effects of the ellipsoid size on the structural characteristics of graphite anode were particularly studied. As the size of the ellipsoidal particle slightly increases, the average pore diameter increases and as a result the specific interfacial area between the solid and pore phase in the reconstructed area decreases; compared with the equatorial radius, the polar radius of ellipsoidal graphite particles has more significant influence on the characteristics of electrode microstructure. The present work developed an ellipsoid-based simulated annealing method and numerically reconstructed the three-dimensional microstructure of a graphite anode. The reconstructed anode is a composite of three clearly distinguished phases: pore (or electrolyte), graphite, and solid additives, well for the nonisotropic heterogeneous characteristic of real graphite anode. characterization analysis of the reconstructed electrode gives information such as the connectivity of individual phase, the The effects of the ellipsoid size on the structural characteristics of graphite anode were studied specifically. As the size of the ellipsoidal particle slightly increases, the average pore diameter increases and as a result the specific interfacial area between the solid and pore p hase in the reconstructed area decreases; compared with the equatorial radius, the polar radius of ellipsoidal graphite particles has more significant influence on the characteristics of electrode microstructure.