The application of Li-ion battery on China large geostationary communications satellite platform will reduce the electrical power subsystem mass and volume, enhance platform capability and increase economy. This article introduces application solution of Li-ion batteries applied on the large, long life and high reliability GEO communications satellite platform. By analyzing in-orbit telemetry from the first flight satellite which launched on 12th, October 2015, Li-ion batteries thermal behavior, battery management results, battery flight performance, cell voltage consistency and balance function are verified. The results can be referred for the recurrent large geostationary communication satellite.