A battery temperature raising system and a control method thereof are provided. The battery temperature raising system includes a power supply that operates a heater attached to a battery module. The heater is configured to increase a battery temperature and a variable resistor mounted on a circuit between the heater and the power supply adjusts a heating value of the heater based on an adjustment state of a resistance value. A heater relay is mounted on the circuit between the heater and the power supply and opens and closes the circuit to selectively turn on/off the heater. A first sensor senses the battery temperature and a second sensor senses a heater temperature. A controller outputs a control signal to operate the heater relay to selectively turn on/off the heater based on temperature information sensed by the sensors and a control signal to adjust the resistance value of the variable resistor.