A vehicle control system mounted on a vehicle is provided. The vehicle control system includes a first sensor configured to sense a driver's pupil size and gaze, a second sensor configured to sense an external object which exists in a peripheral region of the vehicle, a controller configured to sense lane change intention according to a change of the pupil size and the gaze, and in response to the lane change intention being sensed, control the second sensor to sense whether the external object exists in a direction of a lane to be changed, and an output unit configured to, in response to the external object existing in the direction of the lane to be changed, output a warning message.