The invention relates to an intelligent lithium ion battery management system for an electric vehicle. The management system is characterized in that a microcontroller module is connected with a power supply module, a data detection module, a charge-discharge control module, a safety protection module, a communication module, a data storage module and a balance management module. The balance control method comprises the following steps: carrying out balance self-inspection according to each collected single cell voltage data in a cell unit; if the balance self-inspection is successful, judging whether to start balance control; if the difference between the single cell voltage and the average value voltage is larger than a preset threshold voltage and the voltage of a certain single cell is larger than a preset threshold, carrying out balance control with PWM duty ratio obtained based on the single cell voltage being as balance time; or otherwise, giving up carrying out the balance control. The management system in the invention is a centralized battery management system, and has the advantages of small size, stable performance, high detection precision, low cost and high reliability and the like.