The invention relates to an on-line balanced monitoring method for a storage battery pack, and relates to the field of electric power. According to the invention, the problem that some storage batteries are overcharged and the other storage batteries are undercharged in the conventional storage battery pack, the capacity of the conventional storage battery pack is detected by manpower, the workload is heavy, and the efficiency is low can be solved. N battery modules are connected in series to form a storage battery pack, and N back discharge units allow each battery module to normally discharge in an open circuit; N battery activation units monitor the internal resistance of each battery module; N balanced modules monitor the voltage of each battery module in real time; acquisition control units acquire open circuit signals, the internal resistance value, the capacitance value and the voltage value of each battery module, and perform a activation process on the battery module, then transmit a processing result to a main control box; data interaction between the main control box and a server is performed by an Ethernet network, and meanwhile, a current Hall sensor acquires charging and discharging current of the whole storage battery pack; the on-line balanced monitoring method is used for balanced monitoring of the battery pack.