The invention discloses a lithium ion battery management system and a control method thereof, and comprises battery charge and discharge management scheduling, battery information communication and battery life assessment. Adding a battery cell in series or withdrawing the battery cell in a controlled manner is realized by utilizing a switch circuit. Data transmission between series battery cells is realized by utilizing hardware and software forwarding circuits. In a rated charge and discharge condition, through carrying out charge and discharge tests on a lithium ion battery repeatedly, recording charge and discharge times, and voltage curve and battery internal resistance of each charge and discharge operation, constructing a four-dimensional data table, and determining equivalent cycle times and present full charge capacity of the battery by utilizing an interpolation method, an equivalent cycle life of a battery pack is determined. According to the invention, energy transduction devices like an inductance capacitor are not needed, characteristics of batteries in a same battery pack tend to be consistent, a service life of the battery pack is prolonged, overpressure resistant requirements of each component are mitigated, a basic basis of estimating battery full charge capacity and accurate estimation of a battery life is established, and possibility of large scale interchangeability application is provided.