The invention discloses a method for considering real-time operation cleanness factors of a condenser and improving efficiency of a generating set. The method comprises the steps as follows: related data in an operating unit is collected by a real-time operation data collecting and processing system of the condenser, and sent to a real-time operation cleanness factor computing unit and an optimal vacuum computing unit of the condenser; the real-time operation cleanness factor computing unit sequentially computes the real-time operation cleanness factors of the condenser according to the received data, and sends the computation results to the optimal vacuum computing unit of the condenser; the optimal vacuum computing unit of the condenser adopts an iterative computing method to confirm a circulating water flow rate corresponding to the optimal vacuum state of unit operation, and sends a result to a circulating water flow rate real-time control unit and a deviation correction unit; and the circulating water flow rate real-time control unit and the deviation correction unit are matched with each other so that a circulating water flow rate value is close to an optimal vacuum state value. According to the method, the real-time operation cleanness factors of the condenser are considered, and the optimal vacuum state of the unit operation is optimized and confirmed, so that the optimized operation efficiency of a thermal power generating unit is achieved.