The invention provides a determination method and system of power grid wind electricity digestion capability. The method comprises the following steps of collecting load power of a power grid system within a certain period of time; collecting set data of the power grid system within the certain period of time, wherein the set data comprise a set type, a rated capacity, an upper limit and a lower limit of output of heating period, an upper limit and a lower limit of output of non-heating period and set creep speed; collecting foreign area electric power of the power grid system within the certain period of the time; adjusting the output of a set according to the upper limit and the lower limit of the output of the set; adjusting the output of the set according to spare restraint of upper adjustment and lower adjustment of a power grid; and determining the power grid wind electricity digestion capability according to the collected load power, the output, after being adjusted, of the set and the foreign area electric power. Through overall consideration of power balance of the power grid system, states of starting and shutting of each set and the range of the output under the condition of two load levels of peak and low, the multiple factors are uniformly optimized in a mixing integer planning model so as to obtain an optimal solution of the output of wind electricity.