The invention provides a method for dynamic balance control over a lithium ion battery. The method comprises the steps that standing time of the power battery is judged according to finished vehicle parking time; after the standing time is sufficient, the current voltage of the battery is determined to be in the real battery state, and whether balance needs to be conducted or not is judged according to current dropout voltage; meanwhile, an appropriate resistor is chosen to discharge according to the range of the dropout voltage and balance time is controlled. The method for dynamic balance control over the lithium ion battery has the advantages that the balance process occurs in the finished vehicle operation process, namely after the decision that the balance process needs to be conducted is made, a balance order is executed through the method, and a finished vehicle order is responded, so that charging and discharging control over the battery is achieved; according to the dropout voltage of single bodies, the balance resistor can be appropriately chosen and the balance time can be controlled.