The invention discloses a start-stop control method for a balance module of an energy storage system. The start-stop control method comprises the steps of putting the system into operation and starting balancing of various clusters by an energy storage management system; carrying out balancing judgment separately, traversing single bodies of all BMU packages and finding out and recording positions and voltage values of the single bodies with maximum voltage and minimum voltage of each BMU package; comparing the voltage values of the single bodies with the maximum voltage and the minimum voltage of each BMU package with a preset value and judging whether the single bodies require charge and discharge balancing or not; and when balancing needs to be started, adjusting to make sure that the number difference of charge and discharge single bodies in each cluster does not exceed m and the sum of the charge and discharge single bodies in each cluster does not exceed n, stopping all balancing after a period of time and repeating the steps. Normal operation of the energy storage system can be ensured through setting limiting conditions in the balancing process and keeping the number of the charge and discharge single bodies in each cluster balanced within a certain range, meanwhile, the effectiveness of the balancing function of the system can also be ensured, the security is high, and the start-stop control method is widely applied to the field of power systems.