Provided in the invention is a master-slave-type-energy-storage-coordinated-control-based active fluctuation stabilizing and suppressing method for an extra-high-voltage tie line. The invention, whichrelates to the technical field of secondary frequency modulation of a power grid, particularly provides a master-slave-type-energy-storage-coordinated-control-based active fluctuation stabilizing andsuppressing method for extra-high-voltage tie line based on the own frequency modulation characteristic of the BESS so that the actual needs of extra-high-voltage interconnected power grid can be met. Therefore, the decoupling control of the power and frequency fluctuation of the tie line by the BESS is realized; the tie line power fluctuation is suppressed effectively on the premise that the stability of the frequency of the power grid is ensured; and thus the requirement on the exchange power stability of the tie line by the regional power grid in extra-high-voltage connection is met. The control performance standard CPS is used as an evaluation index and an examination index and thus the regional power grid meets the examination index of the grid company.