The invention discloses a method for automatically formulating daily power grid maintenance plans, and particularly relates to a software algorithm through which a power management department formulates maintenance plans of power units at current levels and subordinate power units. The method is suitable for upper-level scheduling running personnel to automatically generate proper maintenance plans under various constraint conditions by integrating power grid running conditions and maintenance plan needs of power grids at all levels; the algorithm acquires power grid topological structure and maintenance plan arrangement at each level from a power grid related system through a software protocol, and a dictionary order is utilized to perform simple and preliminary sequencing on all daily maintenance plans. For a first ergodic maintenance plan after sequencing, searching is performed by means of blackout chain effect. A searching rule is that all equipment have to be in blackout when the maintenance is executed, a maintenance set is formed, and optimized daily maintenance plans are acquired through cyclic iteration adjusting.