The invention relates to an air-cooled steam condensing system with natural ventilation and direct water film evaporation, which comprises a natural ventilation cooling tower and a direct water film evaporation type air-cooled cluster steam condenser arranged above the water pool of the cooling tower. Waste steam from a steam turbine flows through the tube of the steam condenser to release heat so as to be condensed into water to be discharged; and spray water forms a water film outside of the tube, flowing air sweeps the water film, and the water film absorbs the heat of the waste steam in the tube and transmit sensible heat and the latent heat generated in the evaporation of the water film to the flowing air. The spray water then falls into the water pool of the cooling tower, and is delivered to a spray water distribution device above each tube bundle of the steam condenser by a circulating pump. The system consumes a certain amount of evaporated water, thereby significantly improving the heat cycling efficiency. No fan is applied to consume power, thereby reducing the service power. Moreover, the system can overcome the defect that the direct dry-air-cooled steam condensation can not be completed and realized in the high-temperature environment. Compared with the water-cooled steam condensation, the system can obtain a steam condensation temperature lower than the water-cooled steam condensation, achieve higher heat cycling efficiency, and significantly reduce water consumption. Therefore, the system is applicable to areas with abundant water resources but stricter and stricter water-saving requirements.