Nickel-rich ternary layered oxide LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) is considered to be one of the most potential cathode materials in the next generation lithium-ion batteries due to its high reversible capacity, environmentally friendly feature and low cost. However, this kind of cathode material is suffering from the poor thermal stability, phase transition during the charge-discharge process and safety issue, which hinders its further practical application. With the deepening of researches and development of fabrication methods, the electrochemical properties of NCM811 have been significantly improved. In this paper, the recent research progress of nickel-rich layered oxide NCM811 cathode material has been reviewed. We mainly focus on the problems and declined mechanisms, synthesis methods, improvement measures and theoretical calculation simulation studies of NCM811, and also make a brief outlook for the future development of nickel-rich ternary layered oxide NCM811.