NOVELTY - The system (1) has first condenser (10) connected to cooling line (C.L) between radiator (2) and storage tank (8) to introduce cooling fluid, so that refrigerant introduced through a refrigerant line (R.L) is primarily condensed by heat exchange between cooling fluid and refrigerant. A second condenser (20) arranged on front of the radiator, is serially connected to first condenser on refrigerant line, to secondarily condense the primarily condensed refrigerant introduced from first condenser by heat exchange between refrigerant and outdoor air introduced on driving.    USE - Air-conditioning system for vehicle e.g. fuel cell vehicle and electric vehicle.    ADVANTAGE - When the refrigerant is primarily condensed through the cooling fluid, the condensing pressure can be reduced as heat capacity of the cooling fluid is higher than that of the outdoor air, and when the refrigerant is secondarily condensed through the outdoor air, sub-cool effectiveness can be increased as the temperature difference between the cooling fluid and the refrigerant can be high, and hence the overall air-conditioning cooling performance can be improved by increasing the condensing rate of the refrigerant. The required works for the compressor can be reduced through the reduced condensing pressure of the refrigerant, and the water temperature of the cooling fluid can be reduced through the increased sub-cool effectiveness, so that the cooling performance can be improved without increasing the capacity of the radiator and the cooling fan. Hence space utilization can be increased by simplifying a layout in a narrow engine room, and weight reduction can be achieved and the manufacturing cost can be saved.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the air-conditioning system for vehicle. (Drawing includes non-English language text)    Air-conditioning system (1)    Radiator (2)    Storage tank (8)    First and second condensers (10,20)    Cooling line (C.L)    Refrigerant line (R.L)