With the proposal of dual-carbon target, energy storage is an important way to promote distributed PV local balanced consumption and reduce carbon emissions from the distribution network, but the traditional energy storage configuration scheme usually only considers the electric power balance, and how to comprehensively consider the electric-carbon characteristics puts forward higher requirements for the optimal configuration of energy storage. Firstly, a cluster division method based on electrical distance and net load carbon flow rate is proposed by introducing the node net load carbon flow rate index for cluster division of distribution networks, which improves the efficiency of distribution network management and the accuracy of carbon emission management. On the basis of the cluster classification, an energy storage allocation method that takes into account the carbon emission cost of the distribution network is further proposed, which takes into account the carbon emission cost and network loss cost, as well as the economic cost and benefit of energy storage allocation, establishes a carbon balance mechanism for energy storage, quantifies the impact of the change of the carbon content within the energy storage on the distribution network, and avoids carbon dioxide emissions into or out of the energy storage equipment. Finally, the results of an arithmetic simulation in a distribution network in Anhui province show that the proposed method reduces the total carbon emissions of the distribution network by 11.12 % compared to the unconfigured energy storage system.