Abstract: Based on density functional theory of first-principles, band gap, partial density of states, energy of Lithium ion insertion and cell volume of layered structure LiNi0.85-xCoxMn0.15O2 with space group R-3m were calculated. Calculation result showed that LiNi0.85-xCoxMn0.15O2, which owned high reversible capacity and good performance, is perfect for cathode materials of lithium-ion batteries among the metal oxide. Comparing with the reported performances, we noticed that the calculation results match well with the experimental ones.The nickel and cobalt content changed herein adopted Mixture Atom Editor of CASTEP program，and analyzed the physical and electrochemical property of LiNi0.85-xCoxMn0.15O2.This reveal the influence by nickel and cobalt content change to performance of the material for lithium ion battery,and then provode theoretical directions for searching new ternary cathode materials.