The invention relates to a power system unit combination method based on random robust optimization, and belongs to the technical field of power system operation control. The method comprises the following steps: firstly, building a power system unit combination model composed of a target function and a constraint condition; converting the constraint condition, and converting an original model into a nonlinear optimization problem; and solving the converted model to obtain a generator starting plan, and conducting a corresponding starting plan decision according to a solving result to achieveunit combination. According to the method, the fluctuation of renewable energy in a power system is considered, the cost of corrective control is reduced, and the safety of the power system is guaranteed; and the method is suitable to be applied to scenes of day-ahead unit combination and the like of the power system.