Abstract: The virtual inertia constant of grid-following energy storage has time-varying characteristic and the equivalent inertia constant of the system cannot be aggregated and solved, which leads to the failure of constructing a complete system frequency response（SFR） model in the SFR modeling application of the new power system including the virtual inertia control of gridfollowing energy storage. On this basis, the constantized calculation method of the virtual inertia constant for grid-following electrochemical energy storage is proposed, which can aggregate and solve the equivalent inertia constant of the system by calculating the constantized virtual inertia constant with the equivalent inertia constant-energy support effect. The proposed method establishes an objective function with the closest energy change to solve the constantized virtual inertia constant in sections according to the constraints of the key nodes and dynamic process of energy change, and the two-stage different characteristics of the virtual inertia response of grid-following energy storage. Finally, the accuracy of the calculation results is verified by establishing the SFR model which combines the time-domain simulation method and relevant evaluation indices.