A passive cooling system for a reactor core of a large-scale pressurized water reactor nuclear power plant includes a shield building having an outer wall and a through air inlet arranged on an upper part of the outer wall, a water tank arranged at an upper part of the shield building, a cooling water distribution plate arranged above a top of a containment within the shield building, a spray pipe arranged at an inside of the top of the shield building and having a water inlet end and a water outlet end, wherein the water inlet end is connected to a bottom of the water tank and the water outlet end is extended to be above the cooling water distribution plate, and an air deflector arranged between the shield building and the containment and having an upper end connected to an inside of the top of the shield building.