To promote the high-efficiency accommodation of high-penetration distributed energy resources in distribution networks and to satisfy the demand of emerging loads such as electric vehicles, a multi-objective optimal allocation model for E-SOP (energy storage-type flexible soft open point) based on an improved NSWOA (non-dominated whale optimization algorithm) was proposed. First, an E-SOP with higher controllability is integrated by embedding energy storage devices into the DC link of the flexible soft open point. Second, the optimal installation site of the E-SOP was determined by the chronological voltage sensitivity method. Then, a multi-objective optimal allocation model for the E-SOP was established with the objectives of minimizing system operating voltage deviation and power loss. Finally, the Pareto set searched by the NSWOA was adjusted by the quantized screening law for the region angle, by which the solution set is prevented from falling into crowding and the model was effectively solved. Taking the modified IEEE 33-node distribution system as an example, the validity of the proposed model is verified. The results indicate that the optimally allocated ESOP exhibits better controllability and flexibility.