The invention relates to a generating capacity distribution method and device for plant stations. The method comprises the steps of: according to theoretical power prediction accuracy and management level coefficients of the plant stations, determining an evaluation score of each plant station; according to the evaluation score of each plant station, determining instantaneous generated power distributed to each plant station; and according to the instantaneous generated power distributed to each plant station, determining generating capacity distributed to each plant station. According to thetechnical scheme provided by the invention, fairness and impartiality of scheduling are sufficiently shown, each plant station is stimulate to accelerate improvement of the power predication accuracyand the management level, and safety stable operation of a power grid is guaranteed.