In the view of the battery serious aging caused by the constant-current-constant-voltage(CC-CV) charging strategy which adopts the empirical charging current values, this paper proposes an improved CC-CV charging strategy. Firstly, with the goal of minimum decline capacity of battery, the database dynamic programming (DDP) is employed for the planning of the battery life cycle on the basis of the capacity decline model of lithium-ion battery. After that, the corresponding optimal charging current distribution under different cycle stages is obtained, and the influence of the charging current on the battery capacity decay is also analyzed. Finally, in MATLAB/Simulink simulation, the proposed strategy is compared with the existing CC-CV charging strategy. It is shown that this strategy can effectively extend the battery cycle life.