Disclosed is an inside ventilation system of a vehicle for a driver or an occupant to achieve a more comfortable inside environment in the summer or winter. The inside ventilation system includes a control unit configured to receive an operating signal from a smart key, sense an inside temperature of the vehicle when the operating signal is transferred and judging whether the inside temperature is deviated from a required temperature range; a comparison process of comparing the inside temperature and a battery temperature when the inside temperature is deviated from the required temperature range; and a control process of controlling a heating, ventilation, and air conditioning system (HVAC) and an operation of a battery operated fan by comparing the inside temperature and the battery temperature.