A control method of a heat pump system for a vehicle includes a first cooling apparatus having a first radiator, a first water pump, an electrical component, a valve, and a branch line, which are connected by a first coolant line and circulate a first coolant by the first water pump to the electrical component; a second cooling apparatus including a second radiator and a second water pump connected by a second coolant line; and an air conditioning apparatus including a compressor, a heater, an expansion valve, and a heat exchanger which are connected by a refrigerant line circulated with a refrigerant.