The invention discloses an energy storage capacity optimal configuration method adapted to large-scale new energy grid-connected consumption. The method comprises the steps of: determining regional power grid calculation parameters and generating a new energy blocked region set; determining a regional power grid energy storage initial configuration scale and related parameters; establishing an optimal scheduling model; determining a power grid new energy maximum consumption amount of a current new energy blocked region; updating an energy storage configuration scale optimization interval; judging whether to update a system energy storage configuration scale or not; if the judging result is positive, updating the system energy storage configuration scale and re-determining the power grid new energy maximum consumption amount of the current new energy blocked region; if the judging result is negative, judging whether the set is traversed or not; if the set is traversed, determining and outputting energy storage inverter power, battery capacity and energy storage configuration investment cost; and if the set is not completely traversed, re-determining the power grid new energy maximumconsumption amount of the current new energy blocked region. The method is capable of determining the reasonable capacity of energy storage configuration in systems under large-area environment and large time scale.