Li-ion batteries have been widely used to power portable electronic equipments, and have been considered as an alternative source of power for electric or hybrid vehicles. Cathode is a key part of Li-ion battery and determines the battery performance. In this paper, we briefly introduced an important and promising Li-Ni-Co-Mn-O cathode with high capacity and working voltage. The development status, modification methods, and existent issues of Li-Ni-Co-Mn-O cathode were also introduced. And in the end, we propose a possible solution to the issues blocking in application processes.