The present invention relates to a vehicle air-conditioning system and, more particularly, to a vehicle air-conditioning system in which an air-conditioning module consisting of an air-conditioning case and a blowing apparatus is disposed at a side of an engine room with respect to a dash panel, and a distribution duct for distributing cold and hot air discharged from the air-conditioning case into the inside of a vehicle is disposed on the indoor side of the vehicle with respect to the dash panel. The vehicle air-conditioning system may prevent a reverse flow of outdoor air into a cold air discharge port and a hot air discharge port due to the wind pressure when driving by forming a shielding means at the sides of the cold air discharge port and the hot air discharge port, which discharge the cold and hot air of the air-conditioning case to the outside, thereby improving the cooling and heating performance by smoothly discharging heat through the cold air discharge port and the hot air discharge port.