Compared to a single-type energy storage system, a multi-type battery energy storage system can leverage the complementary characteristics of different battery types, enabling enhanced frequency regulation performance, improved flexibility, and higher operational efficiency. However, the integration of multi-types energy storages with different battery characteristics may increase the difficulty of frequency regulation. Considering both frequency regulation costs and the state of charge (SOC) of energy storage, this paper proposes an optimized power allocation strategy which includes the battery energy storage power station (BESPS) level and the battery energy storage unit (BESU) level. At the BESPS level, the objective function combines the remaining frequency regulation capacity and the frequency regulation cost to allocate power in a way that maximizes economic efficiency while accounting for the available capacity of each energy storage station. At the BESU level, the strategy focuses on balancing the SOC across individual energy storage units to avoid overcharging and deep discharging. The proposed strategy is validated by using three types of energy storage stations—sodium-sulfur batteries, vanadium redox flow batteries (VRFBs), and hydrogen storage batteries, while fully accounting for their unique characteristics.