The layered LiNi0.4Co0.2Mn0.4O1.97X0.03 (X=O, F, Cl) samples were prepared by a sol-gel method. The crystal structure, apparent morphology and electrochemical performance were characterized by XRD, SEM, cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS) and charge-discharge tests. The results show that LiNi0.4Co0.2Mn0.4O1.97X0.03 (X=O, F, Cl) samples remain a well-layered structure with single phase of hexagonal after fluorine or chlorine doping. The reversibility of the cathode materials is enhanced by fluorine or chlorine doping. The discharge capacity is increased and cycling property improved. The increase of electrochemical reaction impedance of cathode is restrained after fluorine or chlorine doping during cycling.