A heat pump system for a vehicle which includes a compressor, a condenser, expansion means and an evaporator connected with one another through a refrigerant circulation line, comprising: an air-conditioning case having a cold air passageway that the evaporator is installed and a warm air passageway that the condenser is installed partitioned by a partition wall which partitions the inside of the air-conditioning case; a first blower which is mounted on an inlet of the cold air passageway of the airconditioning case to blow air toward the cold air passageway; a second blower which is mounted on an inlet of the warm air passageway of the airconditioning case to blow air toward the warm air passageway; and an intake duct which is communicatingly mounted between the first blower and the second blower to supply indoor air and outdoor air to the first blower and the second blower; a bypass passageway formed in the partition wall to make some of the warm air passing the condenser in the warm air passageway bypass towards the cold air passageway; a bypass door mounted at one side of the bypass passageway to open and close the bypass passageway (114; a cold air outflow port for discharging the cold air passing through the evaporator to the interior of the vehicle, a cold air discharge port for discharging the cold air to the exterior of the vehicle and a cold air mode door for opening and closing the cold air outflow port, the cold air discharge port being disposed on an outlet side of the cold air passageway of the airconditioning case; a warm air outflow port for discharging the warm air passing through the condenser to the interior of the vehicle; a warm air discharge port for discharging the warm air to the exterior of the vehicle, disposed on an outlet side of the warm air passageway of the air-conditioning case; a warm air mode door for opening and closing the warm air outflow port; characterized in that it comprises a mixing zone formed on the cold air outflow port and the warm air outflow port, where the cold air passing through the cold air outflow port and the warm air passing through the warm air outflow port are mixed, and wherein a plurality of air outflow ports (117a, 117b, 117c) is formed, for discharging the air inside the mixing zone toward the interior and that it comprises a discharge mode door for controlling the degree of opening of the air outflow ports (117a, 117b, 117c) that are disposed on one side of the mixing zone. an air-conditioning case having a cold air passageway that the evaporator is installed and a warm air passageway that the condenser is installed partitioned by a partition wall which partitions the inside of the air-conditioning case; a first blower which is mounted on an inlet of the cold air passageway of the airconditioning case to blow air toward the cold air passageway; a second blower which is mounted on an inlet of the warm air passageway of the airconditioning case to blow air toward the warm air passageway; and an intake duct which is communicatingly mounted between the first blower and the second blower to supply indoor air and outdoor air to the first blower and the second blower; a bypass passageway formed in the partition wall to make some of the warm air passing the condenser in the warm air passageway bypass towards the cold air passageway; a bypass door mounted at one side of the bypass passageway to open and close the bypass passageway (114; a cold air outflow port for discharging the cold air passing through the evaporator to the interior of the vehicle, a cold air discharge port for discharging the cold air to the exterior of the vehicle and a cold air mode door for opening and closing the cold air outflow port, the cold air discharge port being disposed on an outlet side of the cold air passageway of the airconditioning case; a warm air outflow port for discharging the warm air passing through the condenser to the interior of the vehicle; a warm air discharge port for discharging the warm air to the exterior of the vehicle, disposed on an outlet side of the warm air passageway of the air-conditioning case; a warm air mode door for opening and closing the warm air outflow port; characterized in that it comprises a mixing zone formed on the cold air outflow port and the warm air outflow port, where the cold air passing through the cold air outflow port and the warm air passing through the warm air outflow port are mixed, and wherein a plurality of air outflow ports (117a, 117b, 117c) is formed, for discharging the air inside the mixing zone toward the interior and that it comprises a discharge mode door for controlling the degree of opening of the air outflow ports (117a, 117b, 117c) that are disposed on one side of the mixing zone.