The invention discloses a capacity optimization configuration method for a power distribution network composite energy storage device. The method comprises the following steps of: (1), constructing acalculation model of a state of charge (SOC) of the energy storage device, (2) acquiring a load value of an independent microgrid system, (3) proposing an energy distribution strategy based on a low-pass filtering principle, (4) establishing a target function, (5) establishing constraint conditions of the target function, (6) constructing a simulated annealing particle swarm algorithm, (7) acquiring related parameters of a storage battery and a super capacitor, and (8) solving to obtain parameters such as the storage battery capacity, the super capacitor capacity andannual average cost, and further applying the steps (1) and (3) to obtain the charging and discharging power of the storage battery and the super capacitor. By optimizing and configuring the capacity of the power distribution network composite energy storage device, the distributed renewable energy consumption capacity of the power distribution network can be remarkably enhanced, and the power quality and the safety of power supply of the power distribution network under the condition that a high-proportion distributed power supply is connected are improved.