The invention provides a power grid low-frequency load shedding optimal configuration method and system adapting to high-proportion new energy. The method comprises the steps: calculating a new energyoutput proportion of a power grid in a current operation mode; when the power grid breaks down, selecting a low-frequency load shedding configuration scheme from a pre-generated low-frequency configuration scheme table based on the new energy output proportion under the current operation mode of the power grid and the action condition of the safety and stability control device, wherein the low-frequency load shedding configuration scheme table comprises a new energy output proportion, a low-frequency configuration scheme and a configuration parameter value corresponding to the low-frequency configuration scheme. According to the technical scheme provided by the invention, the new energy output proportion under the current operation mode is considered, and it is ensured that after the safety and stability control device acts on the power grid, low-frequency load shedding does not malfunction to cut off a large number of loads.